Thursday, April 22, 2010

difference between linux server and window NT server

LINUX SERVER

Linux is a freely-circulated open source system, which makes it greatly cost-effective for hosts to provide, maintain, and operate. It also has a extremely strong position for both speed and stability. It’s so accepted that the best part of websites are essentially hosted on a Linux operating system.

SECURITY: Although Linux and Windows can both face hacking attempts, for the reason that Linux is open sourced, patches to close security holes are implemented very quickly since so many people contribute to making it better every day.

COST: Yet again, it’s an open source OS, so it doesn’t need any licensing charge for using Linux operating systems. It expenses a smaller amount for the host to offer the service.

1. Linux is free software., Linux is a open-source OS.People can change code .
2. We can Add programs which will help to use your computer better.
3. Linux wants the programmers to extend and redesign it's OS time after time, but with open-source, so you can see what happens and you can edit the OS.
4. The various distributions of Linux come from different companies (i.e LIndows , Lycoris, Red Hat, SuSe, Mandrake, Knopping, Slackware).,Linux is capable of networking, file sharing and being a web server.
5. Linux is very cheap or free.
6. Linux is customizable in a way that Windows is not.
7. Microsoft Windows is a closed-source operating system created by Bill Gates, supreme ruler of the earth. It is gradually losing it's grip on the market because it is insecure, slow, and wasteful.
8. Windows and Linux are two different operating systems. The purpose of an operating system is to: 1. control all the hardware components that are part of your computer. 2. manage a computer's ability to do several things at once 3. provide a base set of services to programs to keep software manufacturers from have to reinvent the wheel a million times for the same thing. The Linux operating system was developed from a base of Unix (another operating system) after the Unix systems stopped being free. The Linux people believe in free and open software, and so they "reinvented" Unix, and improved it slightly to make Linux.
9. Most hard drive installations of Linux utilize a "swap partition", where the disk space allocated for paging is separate from general data, and is used strictly for paging operations. This reduces slowdown due to disk fragmentation from general use.
10. Linux kernel 2.6 once used a scheduling algorithm favoring interactive processes. Here "interactive" is defined as a process that has short bursts of CPU usage rather than long ones. It is said that a process without root privilege can take advantage of this to monopolize the CPU,when the CPU time accounting precision is low. However, Completely Fair Scheduler, now the standard scheduler, addresses this problem

WINDOWS NT SERVER

Windows, similar to your personal computer, is a Microsoft owned commercial operating system. Its major benefit is that it can also run Microsoft software such as Access and MS SQL databases.

SECURITY: Because it is a commercial operating system, it could take a little longer at fixing a few security issues (frequently by releasing security packs) while they must usually be provided through Microsoft.

COST: As you buy Windows for your private computer, servers needs to pay Microsoft for extra licensing amount to make use of their operating system. That’s why hosts generally charge extra for Windows hosting.

1. Window NT is devloped by Microsoft company.
2. Window NT is programmed in C and C++
3. You can't change any thing in windows. you can't even see which processes do what and build your onw extension.
4. All the flavors of Windows come from Microsoft.
5. Windows is expensive
6. Windows is not customizable.
7. Linux is an open source operating system that, until fairly recently, was only used on servers. Now it is used on Mac OS X computers, and more people are starting to use it on computers that aren't servers. It is very secure, efficient, and flexible.
8. Windows and Linux are two different operating systems. The purpose of an operating system is to: 1. control all the hardware components that are part of your computer. 2. manage a computer's ability to do several things at once 3. provide a base set of services to programs to keep software manufacturers from have to reinvent the wheel a million times for the same thing.

Windows is a proprietary operating system owned by Microsoft. It was developed independently from Unix, and its internal details are much different. They should perform the same tasks, however at the deepest levels, details differ, and so a program written to run on Windows will not run on Linux, and vice versa.
Widows comes in several "flavors", like Windows NT, Windows 2000, and Windows XP, all of which are slightly different, but share enough in common that programs written for one flavor will run on the others 99.9% of the time.
9. Windows NT family (including 2000, XP, Vista, Win7) most commonly employs a dynamically allocated pagefile for memory management. A pagefile is allocated on disk, for less frequently accessed objects in memory, leaving more RAM available to actively used objects. This scheme suffers from slow-downs due to disk fragmentation
10. NT-based versions of Windows use a CPU scheduler based on a multilevel feedback queue, with 32 priority levels defined. The kernel may change the priority level of a thread depending on its I/O and CPU usage and whether it is interactive , raising the priority of interactive and I/O bounded processes and lowering that of CPU bound processes, to increase the responsiveness of interactive applications.

Friday, March 26, 2010

Raid Technology

Raid Technology

RAID stands for Redundant Array of Inexpensive (or sometimes "Independent") Disks.

RAID is a method of combining several hard disk drives into one logical unit (two or more disks grouped together to appear as a single device to the host system). RAID technology was developed to address the fault-tolerance and performance limitations of conventional disk storage. It can offer fault tolerance and higher throughput levels than a single hard drive or group of independent hard drives. While arrays were once considered complex and relatively specialized storage solutions, today they are easy to use and essential for a broad spectrum of client/server applications

HISTORY
RAID technology was first defined by a group of computer scientists at the University of California at Berkeley in 1987. The scientists studied the possibility of using two or more disks to appear as a single device to the host system.
Although the array's performance was better than that of large, single-disk storage systems, reliability was unacceptably low. To address this, the scientists proposed redundant architectures to provide ways of achieving storage fault tolerance. In addition to defining RAID levels 1 through 5, the scientists also studied data striping -- a non-redundant array configuration that distributes files across multiple disks in an array. Often known as RAID 0, this configuration actually provides no data protection. However, it does offer maximum throughput for some data-intensive applications such as desktop digital video production.
THE DRIVING FACTORS BEHIND RAID

A number of factors are responsible for the growing adoption of arrays for critical network storage.
More and more organizations have created enterprise-wide networks to improve productivity and streamline information flow. While the distributed data stored on network servers provides substantial cost benefits, these savings can be quickly offset if information is frequently lost or becomes inaccessible. As today's applications create larger files, network storage needs have increased proportionately. In addition, accelerating CPU speeds have outstripped data transfer rates to storage media, creating bottlenecks in today's systems.
RAID storage solutions overcome these challenges by providing a combination of outstanding data availability, extraordinary and highly scalable performance, high capacity, and recovery with no loss of data or interruption of user access.
By integrating multiple drives into a single array -- which is viewed by the network operating system as a single disk drive -- organizations can create cost-effective, minicomputersized solutions of up to a terabyte or more of storage.

RAID LEVELS

There are several different RAID "levels" or redundancy schemes, each with inherent cost, performance, and availability (fault-tolerance) characteristics designed to meet different storage needs. No individual RAID level is inherently superior to any other. Each of the five array architectures is well-suited for certain types of applications and computing environments. For client/server applications, storage systems based on RAID levels 1, 0/1, and 5 have been the most widely used. This is because popular NOSs such as Windows NT® Server and NetWare manage data in ways similar to how these RAID architectures perform.

RAID 0
Data striping without redundancy (no protection).

• Minimum number of drives: 2
• Strengths: Highest performance.

• Weaknesses: No data protection; One drive fails, all data is lost.


DRIVE 1 DRIVE 2
Data A Data A
Data B Data B
Data C Data C

RAID 1
Disk mirroring.

• Minimum number of drives: 2
• Strengths: Very high performance; Very high data protection; Very minimal penalty on write performance.

• Weaknesses: High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required.
Mirroring
Standard Host
Adapter
DRIVE 1 DRIVE 2
Data A Data A
Data B Data B
Data C Data C
Original Data Mirrored Data
Duplexing
Standard Host
Adapter 1 Standard Host
Adapter 2
DRIVE 1 DRIVE 2
Data A Data A
Data B Data B
Data C Data C
Original Data Mirrored Data

RAID 2

No practical use.

• Minimum number of drives: Not used in LAN
• Strengths: Previously used for RAM error environments correction (known as Hamming Code ) and in disk drives before he use of embedded error correction.

• Weaknesses: No practical use; Same performance can be achieved by RAID 3 at lower cost

RAID 3
Byte-level data striping with dedicated parity drive.

• Minimum number of drives: 3
• Strengths: Excellent performance for large, sequential data requests.

• Weaknesses: Not well-suited for transaction-oriented network applications; Single parity drive does not support multiple, simultaneous read and write requests
RAID 4
Block-level data striping with dedicated parity drive.

• Minimum number of drives: 3 (Not widely used)
• Strengths: Data striping supports multiple simultaneous read requests.

• Weaknesses: Write requests suffer from same single parity-drive bottleneck as RAID 3; RAID 5 offers equal data protection and better performance at same cost.,

RAID 5
Block-level data striping with distributed parity.

• Minimum number of drives: 3
• Strengths: Best cost/performance for transaction-oriented networks; Very high performance, very high data protection; Supports multiple simultaneous reads and writes; Can also be optimized for large, sequential requests.

• Weaknesses: Write performance is slower than RAID 0 or RAID 1.
DRIVE 1 DRIVE 2 DRIVE 3
Parity A Data A Data A
Data B Parity B Data B
Data C Data C Parity C

RAID 01(0+1) AND RAID 10(1+0)
Combination of RAID 0 (data striping) and RAID 1 (mirroring). RAID 01 (0+1) is a mirrored configuration of two striped sets (mirror of stripes); RAID 10 (1+0) is a stripe across a number of mirrored sets(stripe of mirrors). RAID 10 provides better fault tolerance and rebuild performance than RAID 01. Both array types provide very good to excellent overall performance by combining the speed of RAID 0 with the redundancy of RAID 1 without requiring parity calculations.

• Minimum number of drives: 4
• Strengths: Highest performance, highest data protection (can tolerate multiple drive failures).

• Weaknesses: High redundancy cost overhead; Because all data is duplicated, twice the storage capacity is required; Requires minimum of four drives

RAID 01 (0+1 mirror of stripes)
DRIVE 1 DRIVE 2 DRIVE 3 DRIVE 4
Data A Data A mA mA
Data B Data B mB mB
Data C Data C mC mC
Original Data Original Data Mirrored Data Mirrored Data

RAID 10 (1+0 stripe of mirrors)
DRIVE 1 DRIVE 2 DRIVE 3 DRIVE 4
Data A mA Data B mB
Data C mC Data D mD
Data E mE Data F mF
Original Data Mirrored Data Original Data Mirrored Data

TYPES OF RAID

There are three primary array implementations: software-based arrays, bus-based array adapters/controllers, and subsystem-based external array controllers. As with the various RAID levels, no one implementation is clearly better than another -- although software-based arrays are rapidly losing favor as high-performance, low-cost array adapters become increasingly available. Each array solution meets different server and network requirements, depending on the number of users, applications, and storage requirements.
It is important to note that all RAID code is based on software. The difference among the solutions is where that software code is executed -- on the host CPU (software-based arrays) or offloaded to an on-board processor (bus-based and external array controllers).
Description Advantages
Software-based RAID Primarily used with entry-level servers, software-based arrays rely on a standard host adapter and execute all I/O commands and mathematically intensive RAID algorithms in the host server CPU. This can slow system performance by increasing host PCI bus traffic, CPU utilization, and CPU interrupts. Some NOSs such as NetWare and Windows NT include embedded RAID software. The chief advantage of this embedded RAID software has been its lower cost compared to higher-priced RAID alternatives. However, this advantage is disappearing with the advent of lower-cost, bus-based array adapters. • Low price
• Only requires a standard controller.
Hardware-based RAID Unlike software-based arrays, bus-based array adapters/controllers plug into a host bus slot [typically a 133 MByte (MB)/sec PCI bus] and offload some or all of the I/O commands and RAID operations to one or more secondary processors. Originally used only with mid- to high-end servers due to cost, lower-cost bus-based array adapters are now available specifically for entry-level server network applications.

In addition to offering the fault-tolerant benefits of RAID, bus-based array adapters/controllers perform connectivity functions that are similar to standard host adapters. By residing directly on a host PCI bus, they provide the highest performance of all array types. Bus-based arrays also deliver more robust fault-tolerant features than embedded NOS RAID software.

As newer, high-end technologies such as Fibre Channel become readily available, the performance advantage of bus-based arrays compared to external array controller solutions may diminish. • Data protection and performance benefits of RAID
• More robust fault-tolerant features and increased performance versus software-based RAID.
External Hardware RAID Card Intelligent external array controllers "bridge" between one or more server I/O interfaces and single- or multiple-device channels. These controllers feature an on-board microprocessor, which provides high performance and handles functions such as executing RAID software code and supporting data caching.

External array controllers offer complete operating system independence, the highest availability, and the ability to scale storage to extraordinarily large capacities (up to a terabyte and beyond). These controllers are usually installed in networks of stand alone Intel-based and UNIX-based servers as well as clustered server environments. • OS independent
• Build super high-capacity storage systems for high-end servers.


SERVER TECHNOLOGY COMPARISON

UDMA SCSI Fibre Channel
Best Suited For Low-cost entry level server with limited expandability Low to high-end server when scalability is desired Server-to-Server campus networks
Advantages • Uses low-cost ATA drives • Performance: up to 160 MB/s
• Reliability
• Connectivity to the largest variety of peripherals
• Expandability • Performance: up to 100 MB/s
• Dual active loop data path capability
• Infinitely scalable

PARITY

The concept behind RAID is relatively simple. The fundamental premise is to be able to recover data on-line in the event of a disk failure by using a form of redundancy called parity. In its simplest form, parity is an addition of all the drives used in an array. Recovery from a drive failure is achieved by reading the remaining good data and checking it against parity data stored by the array. Parity is used by RAID levels 2, 3, 4, and 5. RAID 1 does not use parity because all data is completely duplicated (mirrored). RAID 0, used only to increase performance, offers no data redundancy at all.
A + B + C + D = PARITY


1 + 2 + 3 + 4 = 10
1 + 2 + X + 4 = 10

7 + X = 10
-7 + = -7
--------- ----------
X 3
MISSING RECOVERED
DATA DATA


FAULT TOLERANCE

RAID technology does not prevent drive failures. However, RAID does provide insurance against disk drive failures by enabling real-time data recovery without data loss.
The fault tolerance of arrays can also be significantly enhanced by choosing the right storage enclosure. Enclosures that feature redundant, hot-swappable drives, power supplies, and fans can greatly increase storage subsystem uptime based on a number of widely accepted measures:

• MTDL:
Mean Time to Data Loss. The average time before the failure of an array component causes data to be lost or corrupted.
• MTDA:
Mean Time between Data Access (or availability). The average time before non-redundant components fail, causing data inaccessibility without loss or corruption.
• MTTR:
Mean Time To Repair. The average time required to bring an array storage subsystem back to full fault tolerance.
• MTBF:
Mean Time Between Failure. Used to measure computer component average reliability/life expectancy. MTBF is not as well-suited for measuring the reliability of array storage systems as MTDL, MTTR or MTDA (see below) because it does not account for an array's ability to recover from a drive failure. In addition, enhanced enclosure environments used with arrays to increase uptime can further limit the applicability of MTBF ratings for array solutions

Friday, March 12, 2010

1. You have installed windows service pack 2 and after updating windows up to service pack 3, you are able to log in system but receiving a continuous message that it is not a genuine copy of windows. What are the solutions available to this problem in both manner legal of illegal?
IllegalWindows Genuine Notification popped up because Windows Update again installed it via Automatic Updates. It pops up while a user logs in to windows, displays a message near the system tray and keeps on reminding you in between work that the copy of windows is not genuine. It has been reported since its first release that even genuine users are getting this prompt, so Microsoft has them self release instructions for its removal. When I searched on Google about this issue, I landed up on pages which were providing many methods of its removal including those patching up existing files with their cracked versions which I would highly recommend avoiding them as they might contain malicious code and can be used to get you into more trouble.I found out this method of removal of Windows Genuine Notification :1. Launch Windows Task Manager. 2. End wgatray.exe process in Task Manager. 3. Restart Windows XP in Safe Mode. 4. Delete WgaTray.exe from C:\Windows\System32. 5. Delete WgaTray.exe from C:\Windows\System32\dllcache. 6. Lauch RegEdit. 7. Browse to the following location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify 8. Delete the folder ‘WgaLogon’ and all its contents 9. Reboot Windows XP. But the latest version of the WGN tool is a little tricky to handle. It will pop up again as soon as you end it from the task manager and while it is running in the memory, you can’t delete it too.
IllegalDownload a patch from the Internet and run it in your windows
LegalRegister your windows from Microsoft official website.

2.You have downloaded windows 7 from Microsoft official website in December 2009 on present day your system is rebooting after 2 hours. What are the solutions available to overcome this problem. Legal or Illegal?

Ans:If you have a warm fuzzy feeling inside when thinking about Microsoft and their decision to let you play with their new OS for free until August next year; get ready for the kicker. From March that release candidate you are running is going to start reminding you a commercial copy of the OS needs to be purchased to continue enjoying the benefits of Windows 7 in the most intrusive way possible.You can understand Microsoft wanting to remind users that they need to buy Windows 7, but it’s the method they have decided to employ that is going to annoy and frustrate users. From March 2010 Windows 7 RC will start automatically rebooting your PC every two hours. So, if you happen to be doing something important you’ll have to stop as the friendly “buy me!” shutdown reminder is invoked.For the RC, bi-hourly shutdowns will begin on March 1st, 2010. You will be alerted to install a released version of Windows and your PC will shut down automatically every 2 hours. On June 1st, 2010 if you are still on the Windows 7 RC your license for the Windows 7 RC will expire and the non-genuine experience is triggered where your wallpaper is removed and “This copy of Windows is not genuine” will be displayed in the lower right corner above the taskbar.This isn’t a new tactic Microsoft has implemented to remind users they need to upgrade and it did the same thing with Vista previews. Windows 7 is expected to release in October this year, but at the very latest will be out by January next year giving you plenty of time to buy a copy before the automatic shutdowns begin.

Wednesday, March 10, 2010

NTFS vs FAT

FAT16

FAT32

NTFS

1.) The FAT16 file system was introduced way back with MS–DOS in 1981, and it's showing its age. It was designed originally to handle files on a floppy drive, and has had minor modifications over the years so it can handle hard disks, and even file names longer than the original limitation of 8.3 characters, but it's still the lowest common denominator. The biggest advantage of FAT16 is that it is compatible across a wide variety of operating systems, including Windows 95/98/Me, OS/2, Linux, and some versions of UNIX. The biggest problem of FAT16 is that it has a fixed maximum number of clusters per partition, so as hard disks get bigger and bigger, the size of each cluster has to get larger. In a 2–GB partition, each cluster is 32 kilobytes, meaning that even the smallest file on the partition will take up 32 KB of space. FAT16 also doesn't support compression, encryption, or advanced security using access control lists.
2.) A FAT volume has a maximum size of 2GB and supports MS-DOS as well as being used for some dual boot configurations, but backward compatibility is about the only reason one can think of that FAT should ever be used, other than for the occasional floppy diskette.

1.) The FAT32 file system, originally introduced in Windows 95 Service Pack 2, is really just an extension of the original FAT16 file system that provides for a much larger number of clusters per partition. As such, it greatly improves the overall disk utilization when compared to a FAT16 file system. However, FAT32 shares all of the other limitations of FAT16, and adds an important additional limitation—many operating systems that can recognize FAT16 will not work with FAT32—most notably Windows NT, but also Linux and UNIX as well. Now this isn't a problem if you're running FAT32 on a Windows XP computer and sharing your drive out to other computers on your network—they don't need to know (and generally don't really care) what your underlying file system is.

1.) The NTFS file system, introduced with first version of Windows NT, is a completely different file system from FAT. It provides for greatly increased security, file–by–file compression, quotas, and even encryption. It is the default file system for new installations of Windows XP, and if you're doing an upgrade from a previous version of Windows, you'll be asked if you want to convert your existing file systems to NTFS. Don't worry. If you've already upgraded to Windows XP and didn't do the conversion then, it's not a problem. You can convert FAT16 or FAT32 volumes to NTFS at any point. Just remember that you can't easily go back to FAT or FAT32 (without reformatting the drive or partition), not that I think you'll want to.
The NTFS file system is generally not compatible with other operating systems installed on the same computer, nor is it available when you've booted a computer from a floppy disk. For this reason, many system administrators, myself included, used to recommend that users format at least a small partition at the beginning of their main hard disk as FAT. This partition provided a place to store emergency recovery tools or special drivers needed for reinstallation, and was a mechanism for digging yourself out of the hole you'd just dug into. But with the enhanced recovery abilities built into Windows XP (more on that in a future column), I don't think it's necessary or desirable to create that initial FAT partition.



FAT16, FAT32 and NTFS each use different cluster sizes depending on the size of the volume, and each file system has a maximum number of clusters it can support. The smaller the cluster size, the more efficiently a disk stores information because unused space within a cluster cannot be used by other files; the more clusters supported, the larger the volumes or partitions that can be created.
The table below provides a comparison of volume and default cluster sizes for the different Windows file systems still commonly in use:


Which File System to Choose?
As much as everyone would like for there to be a stock answer to the selection question, there isn't. Different situations and needs will play a large role in the decision of which file system to adopt. There isn't any argument that NTFS offers better security and reliability. Some also say that NTFS is more flexible, but that can get rather subjective depending on the situation and work habits, whereas NTFS superiority in security and reliability is seldom challenged. Listed below are some of the most common factors to consider when deciding between FAT32 and NTFS.
· Security
FAT32 provides very little security. A user with access to a drive using FAT32 has access to the files on that drive.
NTFS allows the use of NTFS Permissions. It's much more difficult to implement, but folder and file access can be controlled individually, down to an an extreme degree if necessary. The down side of using NTFS Permissions is the chance for error and screwing up the system is greatly magnified.
Windows XP Professional supports file encryption.
· Compatibility
NTFS volumes are not recognized by Windows 95/98/Me. This is only a concern when the system is set up for dual or multi-booting. FAT32 must be be used for any drives that must be accessed when the computer is booted from Windows 95/98 or Windows Me.
An additional note to the previous statement. Users on the network have access to shared folders no matter what disk format is being used or what version of Windows is installed.
FAT and FAT32 volumes can be converted to NTFS volumes. NTFS cannot be converted to FAT32 without reformatting.
· Space Efficiency
NTFS supports disk quotas, allowing you to control the amount of disk usage on a per user basis.
NTFS supports file compression. FAT32 does not.
How a volume manages data is outside the scope of this article, but once you pass the 8GB partition size, NTFS handles space management much more efficiently than FAT32. Cluster sizes play an important part in how much disk space is wasted storing files. NTFS provides smaller cluster sizes and less disk space waste than FAT32.
In Windows XP, the maximum partition size that can be created using FAT32 is 32GB. This increases to 16TB (terabytes) using NTFS. There is a workaround for the 32GB limitation under FAT32, but it is a nuisance especially considering the size of drives currently being manufactured.
· Reliability
FAT32 drives are much more susceptible to disk errors.
NTFS volumes have the ability to recover from errors more readily than similar FAT32 volumes.
Log files are created under NTFS which can be used for automatic file system repairs.
NTFS supports dynamic cluster remapping for bad sectors and prevent them from being used in the future.
The Final Choice

As the prior versions of Windows continue to age and are replaced in the home and workplace there will be no need for the older file systems. Hard drives aren't going to get smaller, networks are likely to get larger and more complex, and security is evolving almost daily as more and more users become connected. For all the innovations that Windows 95 brought to the desktop, it's now a virtual dinosaur. Windows 98 is fast on the way out and that leaves NT and Windows 2000, both well suited to NTFS. To wrap up, there may be compelling reasons why your current situation requires a file system other than NTFS or a combination of different systems for compatibility, but if at all possible go with NTFS. Even if you don't utilize its full scope of features, the stability and reliability it offers make it the hands down choice.

Sunday, February 21, 2010

novell netware

Novell NetWare


The NetWare console screen (August 22, 2006)
Company / developer
Novell, Inc.

Working state Current
Source model Closed source

Initial release 1983
Latest stable release
6.5 SP8 / May 6, 2009
Available language(s)
English

Kernel type
Hybrid kernel

Default user interface
Command line interface

License
Proprietary

Official Website
www.novell.com

NetWare is a network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, and the network protocols were based on the archetypal Xerox Network Systems stack.
NetWare has been superseded by Open Enterprise Server (OES). The latest version of NetWare is v6.5 Support Pack 8, which is identical to OES 2 SP1, NetWare Kernel.
History
NetWare evolved from a very simple concept: file sharing instead of disk sharing. In 1983 when the first versions of NetWare were designed, all other competing products were based on the concept of providing shared direct disk access. Novell's alternative approach was validated by IBM in 1984 and helped promote their product.
With Novell NetWare, disk space was shared in the form of NetWare volumes, comparable to DOS volumes. Clients running MS-DOS would run a special terminate and stay resident (TSR) program that allowed them to map a local drive letter to a NetWare volume. Clients had to log in to a server in order to be allowed to map volumes, and access could be restricted according to the login name. Similarly, they could connect to shared printers on the dedicated server, and print as if the printer was connected locally.
At the end of the 1990s, with Internet connectivity booming, the Internet's TCP/IP protocol became dominant on LANs. Novell had introduced limited TCP/IP support in NetWare v3.x (circa 1992) and v4.x (circa 1995), consisting mainly of FTP services and UNIX-style LPR/LPD printing (available in NetWare v3.x), and a Novell-developed webserver (in NetWare v4.x). Native TCP/IP support for the client file and print services normally associated with NetWare was introduced in NetWare v5.0 (released in 1998).
During the early-to-mid 1980s Microsoft introduced their own LAN system in LAN Manager based on the competing NBF protocol. Early attempts to muscle in on NetWare were not successful, but this changed with the inclusion of improved networking support in Windows for Workgroups, and then the hugely successful Windows NT and Windows 95. NT, in particular, offered services similar to those offered by NetWare, but on a system that could also be used on a desktop, and connected directly to other Windows desktops where NBF was now almost universal.
The rise of NetWare
The popular use and growth of Novell NetWare began in 1985 with the simultaneous release of NetWare 286 2.0a and the Intel 80286 16-bit processor. The 80286 CPU featured a new 16-bit protected mode that provided access to up to 16 MB RAM as well as new mechanisms to aid multi-tasking. Prior to the 80286 CPU servers were based on the Intel 8086/8088 8/16-bit processors, which were limited to an address space of 1MB with not more than 640 KB of directly addressable RAM.
The combination of a higher 16 MB RAM limit, 80286 processor feature utilization, and 256 MB NetWare volume size limit allowed reliable, cost-effective server-based local area networks to be built for the first time. The 16 MB RAM limit was especially important, since it made enough RAM available for disk caching to significantly improve performance. This became the key to Novell's performance while also allowing larger networks to be built.
Another significant difference of NetWare 286 was that it was hardware-independent, unlike competing server systems from 3Com. Novell servers could be assembled using any brand system with an Intel 80286 or higher CPU, any MFM, RLL, ESDI, or SCSI hard drive and any 8- or 16-bit network adapter for which Netware drivers were available.
Novell also designed a compact and simple DOS client software program that allowed DOS stations to connect to a server and access the shared server hard drive. While the NetWare server file system introduced a new, proprietary file system design, it looked like a standard DOS volume to the workstation, ensuring compatibility with all existing DOS programs.
Early years
NetWare was based on the consulting work by SuperSet Software, a group founded by the friends Drew Major, Dale Neibaur, Kyle Powell and later Mark Hurst. This work was based on their classwork at Brigham Young University in Provo, Utah, starting in October 1981.
In 1983, Raymond Noorda engaged the work by the SuperSet team. The team was originally assigned to create a CP/M disk sharing system to help network the CP/M hardware that Novell was selling at the time. The team was privately convinced that CP/M was a doomed platform and instead came up with a successful file sharing system for the newly introduced IBM-compatible PC. They also wrote an application called Snipes, a text-mode game and used it to test the new network and demonstrate its capabilities. Snipes was the first network application ever written for a commercial personal computer, and it is recognized as one of the precursors of many popular multiplayer games such as Doom and Quake.
This network operating system (NOS) was later called Novell NetWare. NetWare was based on the NetWare Core Protocol (NCP), which is a packet-based protocol that enables a client to send requests to and receive replies from a NetWare server. Initially NCP was directly tied to the IPX/SPX protocol, and NetWare communicated natively using only IPX/SPX.
The first product to bear the NetWare name was released in 1983. It was called Netware 68 (aka S-Net); it ran on the Motorola 68000 processor on a proprietary Novell-built file server and used a star network topology. This was soon joined by NetWare 86 V4.x, which was written for the Intel 8086. This was replaced in 1985 with Advanced NetWare 86 version 1.0a which allowed more than one server on the same network. In 1986, after the Intel 80286 processor became available, Novell released Advanced NetWare 286 V1.0a and subsequently V2.0B (that used IPX routing to allow up to 4 network cards in a server). In 1989, with the Intel 80386 available, Novell released NetWare 386. Later Novell consolidated the numbering of their NetWare releases, with NetWare 386 becoming NetWare 3.x.
NetWare 286 2.x
NetWare version 2 was notoriously difficult to configure, since the operating system was provided as a set of compiled object modules that required configuration and linking. Compounding this inconvenience was that the process was designed to run from multiple diskettes, which was slow and unreliable. Any change to the operating system required a re-linking of the kernel and a reboot of the system, requiring at least 20 diskette swaps. An additional complication in early versions was that the installation contained a proprietary low-level format program for MFM hard drives, which was run automatically before the software could be loaded, called COMPSURF.
NetWare was administered using text-based utilities such as SYSCON. The file system used by NetWare 2 was NetWare File System 286, or NWFS 286, supporting volumes of up to 256 MB. NetWare 286 recognized 80286 protected mode, extending NetWare's support of RAM from 1 MB to the full 16 MB addressable by the 80286. A minimum of 2 MB was required to start up the operating system; any additional RAM was used for FAT, DET and file caching. Since 16-bit protected mode was implemented the i80286 and every subsequent Intel x86 processor, NetWare 286 version 2.x would run on any 80286 or later compatible processor.
NetWare 2 implemented a number of features inspired by mainframe and minicomputer systems that were not available in other operating systems of the day. The System Fault Tolerance (SFT) features included standard read-after-write verification (SFT-I) with on-the-fly bad block re-mapping (at the time, disks did not have that feature built in) and software RAID1 (disk mirroring, SFT-II). The Transaction Tracking System (TTS) optionally protected files against incomplete updates. For single files, this required only a file attribute to be set. Transactions over multiple files and controlled roll-backs were possible by programming to the TTS API.
NetWare 286 2.x supported two modes of operation: dedicated and non-dedicated. In dedicated mode, the server used DOS only as a boot loader to execute the operating system file net$os.exe. All memory was allocated to NetWare; no DOS ran on the server. For non-dedicated operation, DOS 3.3 or higher would remain in memory, and the processor would time-slice between the DOS and NetWare programs, allowing the server computer to be used simultaneously as network file server and as a user workstation. All extended memory (RAM above 1 MB) was allocated to NetWare, so DOS was limited to only 640kB; an expanded memory manager would not work because NetWare 286 had control of 80286 protected mode and the upper RAM, both of which were required for DOS to use expanded memory. Time slicing was accomplished using the keyboard interrupt. This feature required strict compliance with the IBM PC design model, otherwise performance was affected. Non-dedicated NetWare was popular on small networks, although it was more susceptible to lockups due to DOS program problems. In some implementations, users would experience significant network slowdown when someone was using the console as a workstation. NetWare 386 3.x and later supported only dedicated operation.
Server licensing on early versions of NetWare 286 was accomplished by using a key card. The key card was designed for an 8-bit ISA bus, and had a serial number encoded on a ROM chip. The serial number had to match the serial number of the NetWare software running on the server. To broaden the hardware base, particularly to machines using the IBM MCA bus, later versions of NetWare 2.x did not require the key card; serialised license floppy disks were used in place of the key cards.
NetWare 3.x
Starting with NetWare 3.x, support for 32-bit protected mode was added, eliminating the 16 mb memory limit of NetWare 286. This allowed larger hard drives to be supported, since NetWare 3.x cached (copied) the entire file allocation table (FAT) and directory entry table (DET) into memory for improved performance.
By accident or design, the initial releases of the client TSR programs modified the high 16 bits of the 32-bit 80386 registers, making them unusable by any other program until this was fixed. The problem was noticed by Phil Katz who added a switch to his PKZIP suite of programs to enable 32-bit register use only when the Netware TSRs were not present.
NetWare version 3 eased development and administration by modularization. Each functionality was controlled by a software module called a NetWare Loadable Module (NLM) loaded either at startup or when it was needed. It was then possible to add functionality such as anti-virus software, backup software, database and web servers, long name support (standard filenames were limited to 8 characters plus a three letter extension, matching MS-DOS) or Macintosh style files.
NetWare continued to be administered using console-based utilities. The file system introduced by NetWare 3.x and used by default until NetWare 5.x was NetWare File System 386, or NWFS 386, which significantly extended volume capacity (1 TB, 4 GB files) and could handle up to 16 volume segments spanning multiple physical disk drives. Volume segments could be added while the server was in use and the volume was mounted, allowing a server to be expanded without interruption.
Initially, NetWare used Bindery services for authentication. This was a stand-alone database system where all user access and security data resided individually on each server. When an infrastructure contained more than one server, users had to log-in to each of them individually, and each server had to be configured with the list of all allowed users.
"NetWare Name Services" was a product that allowed user data to be extended across multiple servers, and the Windows "Domain" concept is functionally equivalent to NetWare v3.x Bindery services with NetWare Name Services added on (e.g. a 2-dimensional database, with a flat namespace and a static schema).
For a while, Novell also marketed an OEM version of NetWare 3, called Portable NetWare, together with OEMs such as Hewlett-Packard, DEC and Data General, who ported Novell source code to run on top of their Unix operating systems. Portable NetWare did not sell well.
While Netware 3.x was current, Novell introduced its first high-availability clustering system, named NetWare SFT-III, which allowed a logical server to be completely mirrored to a separate physical machine. Implemented as a shared-nothing cluster, under SFT-III the OS was logically split into an interrupt-driven I/O engine and the event-driven OS core. The I/O engines serialized their interrupts (disk, network etc.) into a combined event stream that was fed to two identical copies of the system engine through a fast (typically 100 Mbit/s) inter-server link. Because of its non-preemptive nature, the OS core, stripped of non-deterministic I/O, behaves deterministically, like a large finite state machine.
The outputs of the two system engines were compared to ensure proper operation, and two copies fed back to the I/O engines. Using the existing SFT-II software RAID functionality present in the core, disks could be mirrored between the two machines without special hardware. The two machines could be separated as far as the server-to-server link would permit. In case of a server or disk failure, the surviving server could take over client sessions transparently after a short pause since it had full state information and did not, for example, have to re-mount the volumes - a process at which NetWare was notoriously slow. SFT-III was the first NetWare version able to make use of SMP hardware - the I/O engine could optionally be run on its own CPU. The modern incarnation of NetWare's clustering, Novell Cluster Services (introduced in NetWare v5.0), is very different from SFT-III. NetWare SFT-III, ahead of its time in several ways, was a mixed success.
NetWare 386 3.x was designed to run all applications on the server at the same level of processor memory protection, known as "ring 0". While this provided the best possible performance, it sacrificed reliability. The result was that crashing (known as abends, short for abnormal ends) were possible and would result in stopping the system. Starting with NetWare 5.x, software modules (NetWare Loadable Modules or NLM's) could be assigned to run in different processor protection rings, ensuring that a software error would not crash the system.
NetWare 4.x
Version 4 in 1993 also introduced NetWare Directory Services, later re-branded as Novell Directory Services (NDS), based on X.500, which replaced the Bindery with a global directory service, in which the infrastructure was described and managed in a single place. Additionally, NDS provided an extensible schema, allowing the introduction of new object types. This allowed a single user authentication to NDS to govern access to any server in the directory tree structure. Users could therefore access network resources no matter on which server they resided, although user license counts were still tied to individual servers. (Large enterprises could opt for a license model giving them essentially unlimited per-server users if they let Novell audit their total user count)
Version 4 also introduced a number of useful tools and features, such as transparent compression at file system level and RSA public/private encryption.
Another new feature was the NetWare Asynchronous Services Interface (NASI). It allowed network sharing of multiple serial devices, such as modems. Client port redirection occurred via an MS-DOS or Microsoft Windows driver allowing companies to consolidate modems and analog phone lines.[2]
Strategic mistakes
Novell's strategy with NetWare 286 2.x and 3.x was very successful; before the arrival of Windows NT Server, Novell claimed 90% of the market for PC based servers.
While the design of NetWare 3.x and later involved a DOS partition to load NetWare server files, this feature became a liability as new users preferred the Windows graphical interface to learning DOS commands necessary to build and control a NetWare server. Novell could have eliminated this technical liability by retaining the design of NetWare 286, which installed the server file into a Novell partition and allowed the server to boot from the Novell partition without creating a bootable DOS partition. Novell finally added support for this in a Support Pack for NetWare 6.5.
As Novell used IPX/SPX instead of TCP/IP, they were poorly positioned to take advantage of the Internet in 1995. This resulted in Novell servers being bypassed for routing and Internet access, in favor of hardware routers, Unix-based operating systems such as FreeBSD, and SOCKS and HTTP Proxy Servers on Windows and other operating systems.[citation needed]
NetWare 4.1x and NetWare for Small Business: Novell begins to recover
Novell priced NetWare 4.10 similarly to NetWare 3.12, allowing customers who resisted NDS (typically small businesses) to try it at no cost.
Later Novell released NetWare version 4.11 in 1996 which included many enhancements that made the operating system easier to install, easier to operate, faster, and more stable. It also included the first full 32-bit client for Microsoft Windows-based workstations, SMP support and the NetWare Administrator (NWADMIN or NWADMN32), a GUI-based administration tool for NetWare. Previous administration tools used the Cworthy interface, the character-based GUI tools such as SYSCON and PCONSOLE with blue text-based background. Some of these tools survive to this day, for instance MONITOR.NLM.
Novell packaged NetWare 4.11 with its Web server, TCP/IP support and Netscape browser into a bundle dubbed IntranetWare (also written as intraNetWare). A version designed for networks of 25 or fewer users was named IntranetWare for Small Business and contained a limited version of NDS and tried to simplify NDS administration. The intranetWare name was dropped in NetWare 5.
During this time Novell also began to leverage its directory service, NDS, by tying their other products into the directory. Their e-mail system, GroupWise, was integrated with NDS, and Novell released many other directory-enabled products such as ZENworks and BorderManager.
NetWare still required IPX/SPX as NCP used it, but Novell started to acknowledge the demand for TCP/IP with NetWare 4.11 by including tools and utilities that made it easier to create intranets and link networks to the Internet. Novell bundled tools, such as the IPX/IP gateway, to ease the connection between IPX workstations and IP networks. It also began integrating Internet technologies and support through features such as a natively hosted web server.
NetWare 5.x
With the release of NetWare 5 in October 1998, Novell finally acknowledged the prominence of the Internet by switching its primary NCP interface from the IPX/SPX network protocol to TCP/IP. IPX/SPX was still supported, but the emphasis shifted to TCP/IP. Novell also added a GUI to NetWare. Other new features were:
• Novell Storage Services (NSS), a new file system to replace the traditional NetWare File System - which was still supported
• Java virtual machine for NetWare
• Novell Distributed Print Services (NDPS)
• ConsoleOne, a new Java-based GUI administration console
• directory-enabled Public key infrastructure services (PKIS)
• directory-enabled DNS and DHCP servers
• support for Storage Area Networks (SANs)
• Novell Cluster Services (NCS)
• Oracle 8i with a 5-user license
The Cluster Services were a major advance over SFT-III, as NCS does not require specialized hardware or identical server configurations.
NetWare 5 was released during a time when NetWare market share dropped precipitously; many companies and organizations were replacing their NetWare servers with servers running Microsoft's Windows NT operating system. Novell also released their last upgrade to the NetWare 4 operating system, NetWare 4.2.
NetWare 5.1 was released in January 2000, shortly after its predecessor. It introduced a number of useful tools, such as:
• IBM WebSphere Application Server
• NetWare Management Portal (later renamed Novell Remote Manager), web-based management of the operating system
• FTP, NNTP and streaming media servers
• NetWare Web Search Server
• WebDAV support
NetWare 6.0
NetWare 6 was released in October 2001. This version has a simplified licensing scheme based on users, not servers. This allows unlimited connections per user.
NetWare 6.5
NetWare 6.5 was released in August 2003. Some of the new features in this version were:
• more open-source products such as PHP, MySQL and OpenSSH
• a port of the Bash shell and a lot of traditional Unix utilities such as wget, grep, awk and sed to provide additional capabilities for scripting
• iSCSI support (both target and initiator)
• Virtual Office - an "out of the box" web portal for end users providing access to e-mail, personal file storage, company address book, etc.
• Domain controller functionality
• Universal password
• DirXML Starter Pack - synchronization of user accounts with another eDirectory tree, a Windows NT domain or Active Directory.
• exteNd Application Server - a J2EE 1.3-compatible application server
• support for customized printer driver profiles and printer usage auditing
• NX bit support
• support for USB storage devices
• support for encrypted volumes
The latest - and apparently last - Service Pack for Netware 6.5 is SP8, released October 2008.
Open Enterprise Server
Main article: Novell Open Enterprise Server
1.0
In 2003, Novell announced the successor product to NetWare: Open Enterprise Server (OES). First released in March 2005, OES completes the separation of the services traditionally associated with NetWare (e.g. Directory Services, file-and-print) from the platform underlying the delivery of those services. OES is essentially a set of applications (eDirectory, NetWare Core Protocol services, iPrint, etc.) that can run atop either a Linux or a NetWare kernel platform. Clustered OES implementations can even migrate services from Linux to NetWare and back again, making Novell one of the very few vendors to offer a multi-platform clustering solution.
Consequent to Novell's acquisitions of Ximian and SuSE, a German Linux distributor, it is widely observed that Novell is moving away from NetWare and shifting its focus towards Linux. Much recent marketing seems to be focussed on getting faithful NetWare users to move to the Linux platform in future releases. The clearest indication of this direction is Novell's controversial decision to release Open Enterprise Server in Linux form only. Novell later watered down this decision and stated that NetWare's 90 million users would be supported until at least 2015. Some of Novell's more perverse NetWare supporters have taken it upon themselves to petition Novell to keep NetWare in development.
2.0
OES 2 was released on October 8, 2007. It includes NetWare 6.5 SP7, which supports running as a paravirtualized guest inside the Xen hypervisor and new Linux based version using SLES10.
New features include
• 64bit support
• Virtualization
• Dynamic Storage Technology, which provide Shadow Volumes
• Domain services for Windows (provided in OES 2 service pack 1)
Current NetWare situation
While Novell NetWare is still used by some organizations, its ongoing decline in popularity began in the mid-1990s, when NetWare was the de facto standard for file and print software for the Intel x86 server platform. Modern (2009) NetWare and OES installations are used by larger organizations that may need the added flexibility they provide.
Microsoft successfully shifted market share away from NetWare products toward their own in the late-1990s. Microsoft's more aggressive marketing was aimed directly to management through major magazines; Novell NetWare's was through IT specialist magazines with distribution limited to select IT personnel.
Novell did not adapt their pricing structure accordingly and NetWare sales suffered at the hands of those corporate decision makers whose valuation was based on initial licensing fees. As a result organizations that still use NetWare, eDirectory, and Novell software often have a hybrid infrastructure of NetWare, Linux, and Windows servers.
Netware Lite / Personal Netware
In 1991 Novell introduced a radically different and cheaper product - Netware Litez in answer to Artisoft's similar LANtastic. Both were peer to peer systems, where no specialist server was required, but instead all PCs on the network could share their resources.
The product line became Personal Netware in 1993.
Performance
NetWare dominated the network operating system (NOS) market from the mid-80s through the mid- to late-90s due to its extremely high performance relative to other NOS technologies. Most benchmarks during this period demonstrated a 5:1 to 10:1 performance advantage over products from Microsoft, Banyan, and others. One noteworthy benchmark NetWare 3.x running NFS services over TCP/IP (not NetWare's native IPX protocol) to a dedicated Auspex NFS server and a SCO Unix server running NFS service. NetWare NFS outperformed both 'native' NFS systems and claimed a 2:1 performance advantage over SCO Unix NFS on the same hardware. There were several reasons for NetWare's performance.
File service instead of disk service
At the time NetWare was first developed, nearly all LAN storage was based on the disk server model. This meant that if a client computer wanted to read a particular block from a particular file it would have to issue the following requests across the relatively slow LAN:
1. Read first block of directory
2. Continue reading subsequent directory blocks until the directory block containing the information on the desired file was found, could be many directory blocks
3. Read through multiple file entry blocks until the block containing the location of the desired file block was found, could be many directory blocks
4. Read the desired data block
NetWare, since it was based on a file service model, interacted with the client at the file API level:
1. Send file open request (if this hadn't already been done)
2. Send a request for the desired data from the file
All of the work of searching the directory to figure out where the desired data was physically located on the disk was performed at high speed locally on the server. By the mid-1980s, most NOS products had shifted from the disk service to the file service model. Today, the disk service model is making a comeback, see SAN.
Aggressive caching
From the start, NetWare was designed to be used on servers with copious amounts of RAM. The entire file allocation table (FAT) was read into RAM when a volume was mounted, thereby requiring a minimum amount of RAM proportional to online disk space; adding a disk to a server would often require a RAM upgrade as well. Unlike most competing network operating systems prior to Windows NT, NetWare automatically used all otherwise unused RAM for caching active files, employing delayed write-backs to facilitate re-ordering of disk requests (elevator seeks). An unexpected shutdown could therefore corrupt data, making an uninterruptible power supply practically a mandatory part of a server installation.
The default dirty cache delay time was fixed at 2.2 seconds in NetWare 286 versions 2.x. Starting with NetWare 386 3.x, the dirty disk cache delay time and dirty directory cache delay time settings controlled the amount of time the server would cache changed ("dirty") data before saving (flushing) the data to a hard drive. The default setting of 3.3 seconds could be decreased to 0.5 seconds but not reduced to zero, while the maximum delay was 10 seconds. The option to increase the cache delay to 10 seconds provided a significant performance boost. Windows 2000 and 2003 server do not allow adjustment to the cache delay time. Instead, they use an algorithm that adjusts cache delay.
Efficiency of NetWare Core Protocol (NCP)
Most network protocols in use at the time NetWare was developed didn't trust the network to deliver messages. A typical client file read would work something like this:
1. Client sends read request to server
2. Server acknowledges request
3. Client acknowledges acknowledgement
4. Server sends requested data to client
5. Client acknowledges data
6. Server acknowledges acknowledgement
In contrast, NCP was based on the idea that networks worked perfectly most of the time, so the reply to a request served as the acknowledgement. Here is an example of a client read request using this model:
1. Client sends read request to server
2. Server sends requested data to client
All requests contained a sequence number, so if the client didn't receive a response within an appropriate amount of time it would re-send the request with the same sequence number. If the server had already processed the request it would resend the cached response, if it had not yet had time to process the request it would only send a "positive acknowledgement". The bottom line to this 'trust the network' approach was a 2/3 reduction in network transactions and the associated latency.

Non-preemptive OS designed for network services
One of the raging debates of the 90s was whether it was more appropriate for network file service to be performed by a software layer running on top of a general purpose operating system, or by a special purpose operating system. NetWare was a special purpose operating system, not a timesharing OS. It was written from the ground up as a platform for client-server processing services. Initially it focused on file and print services, but later demonstrated its flexibility by running database, email, web and other services as well. It also performed efficiently as a router, supporting IPX, TCP/IP, and Appletalk, though it never offered the flexibility of a 'hardware' router.
In 4.x and earlier versions, NetWare did not support preemption, virtual memory, graphical user interfaces, etc. Processes and services running under the NetWare OS were expected to be cooperative, that is to process a request and return control to the OS in a timely fashion. On the down side, this trust of application processes to manage themselves could lead to a misbehaving application bringing down the server.
By comparison, general purpose operating systems such as Unix or Microsoft Windows were based on an interactive, time-sharing model where competing programs would consume all available resources if not held in check by the Operating System. Such environments operated by preemption, memory virtualization, etc., generating significant overhead because there were never enough resources to do everything every application desired. These systems improved over time as network services shed their “application” stigma and moved deeper into the kernel of the “general purpose” OS, but they never equaled the efficiency of NetWare

Probably the single greatest reason for Novell's success during the 80's and 90's was the efficiency of NetWare compared to general purpose operating systems. However, as microprocessors increased in power, efficiency became less and less of an issue. With the introduction of the Pentium processor, NetWare's performance advantage began to be outweighed by the complexity of managing and developing applications for the NetWare environment.[

novell netware

Novell NetWare


The NetWare console screen (August 22, 2006)
Company / developer
Novell, Inc.

Working state Current
Source model Closed source

Initial release 1983
Latest stable release
6.5 SP8 / May 6, 2009
Available language(s)
English

Kernel type
Hybrid kernel

Default user interface
Command line interface

License
Proprietary

Official Website
www.novell.com

NetWare is a network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a personal computer, and the network protocols were based on the archetypal Xerox Network Systems stack.
NetWare has been superseded by Open Enterprise Server (OES). The latest version of NetWare is v6.5 Support Pack 8, which is identical to OES 2 SP1, NetWare Kernel.
History
NetWare evolved from a very simple concept: file sharing instead of disk sharing. In 1983 when the first versions of NetWare were designed, all other competing products were based on the concept of providing shared direct disk access. Novell's alternative approach was validated by IBM in 1984 and helped promote their product.
With Novell NetWare, disk space was shared in the form of NetWare volumes, comparable to DOS volumes. Clients running MS-DOS would run a special terminate and stay resident (TSR) program that allowed them to map a local drive letter to a NetWare volume. Clients had to log in to a server in order to be allowed to map volumes, and access could be restricted according to the login name. Similarly, they could connect to shared printers on the dedicated server, and print as if the printer was connected locally.
At the end of the 1990s, with Internet connectivity booming, the Internet's TCP/IP protocol became dominant on LANs. Novell had introduced limited TCP/IP support in NetWare v3.x (circa 1992) and v4.x (circa 1995), consisting mainly of FTP services and UNIX-style LPR/LPD printing (available in NetWare v3.x), and a Novell-developed webserver (in NetWare v4.x). Native TCP/IP support for the client file and print services normally associated with NetWare was introduced in NetWare v5.0 (released in 1998).
During the early-to-mid 1980s Microsoft introduced their own LAN system in LAN Manager based on the competing NBF protocol. Early attempts to muscle in on NetWare were not successful, but this changed with the inclusion of improved networking support in Windows for Workgroups, and then the hugely successful Windows NT and Windows 95. NT, in particular, offered services similar to those offered by NetWare, but on a system that could also be used on a desktop, and connected directly to other Windows desktops where NBF was now almost universal.
The rise of NetWare
The popular use and growth of Novell NetWare began in 1985 with the simultaneous release of NetWare 286 2.0a and the Intel 80286 16-bit processor. The 80286 CPU featured a new 16-bit protected mode that provided access to up to 16 MB RAM as well as new mechanisms to aid multi-tasking. Prior to the 80286 CPU servers were based on the Intel 8086/8088 8/16-bit processors, which were limited to an address space of 1MB with not more than 640 KB of directly addressable RAM.
The combination of a higher 16 MB RAM limit, 80286 processor feature utilization, and 256 MB NetWare volume size limit allowed reliable, cost-effective server-based local area networks to be built for the first time. The 16 MB RAM limit was especially important, since it made enough RAM available for disk caching to significantly improve performance. This became the key to Novell's performance while also allowing larger networks to be built.
Another significant difference of NetWare 286 was that it was hardware-independent, unlike competing server systems from 3Com. Novell servers could be assembled using any brand system with an Intel 80286 or higher CPU, any MFM, RLL, ESDI, or SCSI hard drive and any 8- or 16-bit network adapter for which Netware drivers were available.
Novell also designed a compact and simple DOS client software program that allowed DOS stations to connect to a server and access the shared server hard drive. While the NetWare server file system introduced a new, proprietary file system design, it looked like a standard DOS volume to the workstation, ensuring compatibility with all existing DOS programs.
Early years
NetWare was based on the consulting work by SuperSet Software, a group founded by the friends Drew Major, Dale Neibaur, Kyle Powell and later Mark Hurst. This work was based on their classwork at Brigham Young University in Provo, Utah, starting in October 1981.
In 1983, Raymond Noorda engaged the work by the SuperSet team. The team was originally assigned to create a CP/M disk sharing system to help network the CP/M hardware that Novell was selling at the time. The team was privately convinced that CP/M was a doomed platform and instead came up with a successful file sharing system for the newly introduced IBM-compatible PC. They also wrote an application called Snipes, a text-mode game and used it to test the new network and demonstrate its capabilities. Snipes was the first network application ever written for a commercial personal computer, and it is recognized as one of the precursors of many popular multiplayer games such as Doom and Quake.
This network operating system (NOS) was later called Novell NetWare. NetWare was based on the NetWare Core Protocol (NCP), which is a packet-based protocol that enables a client to send requests to and receive replies from a NetWare server. Initially NCP was directly tied to the IPX/SPX protocol, and NetWare communicated natively using only IPX/SPX.
The first product to bear the NetWare name was released in 1983. It was called Netware 68 (aka S-Net); it ran on the Motorola 68000 processor on a proprietary Novell-built file server and used a star network topology. This was soon joined by NetWare 86 V4.x, which was written for the Intel 8086. This was replaced in 1985 with Advanced NetWare 86 version 1.0a which allowed more than one server on the same network. In 1986, after the Intel 80286 processor became available, Novell released Advanced NetWare 286 V1.0a and subsequently V2.0B (that used IPX routing to allow up to 4 network cards in a server). In 1989, with the Intel 80386 available, Novell released NetWare 386. Later Novell consolidated the numbering of their NetWare releases, with NetWare 386 becoming NetWare 3.x.
NetWare 286 2.x
NetWare version 2 was notoriously difficult to configure, since the operating system was provided as a set of compiled object modules that required configuration and linking. Compounding this inconvenience was that the process was designed to run from multiple diskettes, which was slow and unreliable. Any change to the operating system required a re-linking of the kernel and a reboot of the system, requiring at least 20 diskette swaps. An additional complication in early versions was that the installation contained a proprietary low-level format program for MFM hard drives, which was run automatically before the software could be loaded, called COMPSURF.
NetWare was administered using text-based utilities such as SYSCON. The file system used by NetWare 2 was NetWare File System 286, or NWFS 286, supporting volumes of up to 256 MB. NetWare 286 recognized 80286 protected mode, extending NetWare's support of RAM from 1 MB to the full 16 MB addressable by the 80286. A minimum of 2 MB was required to start up the operating system; any additional RAM was used for FAT, DET and file caching. Since 16-bit protected mode was implemented the i80286 and every subsequent Intel x86 processor, NetWare 286 version 2.x would run on any 80286 or later compatible processor.
NetWare 2 implemented a number of features inspired by mainframe and minicomputer systems that were not available in other operating systems of the day. The System Fault Tolerance (SFT) features included standard read-after-write verification (SFT-I) with on-the-fly bad block re-mapping (at the time, disks did not have that feature built in) and software RAID1 (disk mirroring, SFT-II). The Transaction Tracking System (TTS) optionally protected files against incomplete updates. For single files, this required only a file attribute to be set. Transactions over multiple files and controlled roll-backs were possible by programming to the TTS API.
NetWare 286 2.x supported two modes of operation: dedicated and non-dedicated. In dedicated mode, the server used DOS only as a boot loader to execute the operating system file net$os.exe. All memory was allocated to NetWare; no DOS ran on the server. For non-dedicated operation, DOS 3.3 or higher would remain in memory, and the processor would time-slice between the DOS and NetWare programs, allowing the server computer to be used simultaneously as network file server and as a user workstation. All extended memory (RAM above 1 MB) was allocated to NetWare, so DOS was limited to only 640kB; an expanded memory manager would not work because NetWare 286 had control of 80286 protected mode and the upper RAM, both of which were required for DOS to use expanded memory. Time slicing was accomplished using the keyboard interrupt. This feature required strict compliance with the IBM PC design model, otherwise performance was affected. Non-dedicated NetWare was popular on small networks, although it was more susceptible to lockups due to DOS program problems. In some implementations, users would experience significant network slowdown when someone was using the console as a workstation. NetWare 386 3.x and later supported only dedicated operation.
Server licensing on early versions of NetWare 286 was accomplished by using a key card. The key card was designed for an 8-bit ISA bus, and had a serial number encoded on a ROM chip. The serial number had to match the serial number of the NetWare software running on the server. To broaden the hardware base, particularly to machines using the IBM MCA bus, later versions of NetWare 2.x did not require the key card; serialised license floppy disks were used in place of the key cards.
NetWare 3.x
Starting with NetWare 3.x, support for 32-bit protected mode was added, eliminating the 16 mb memory limit of NetWare 286. This allowed larger hard drives to be supported, since NetWare 3.x cached (copied) the entire file allocation table (FAT) and directory entry table (DET) into memory for improved performance.
By accident or design, the initial releases of the client TSR programs modified the high 16 bits of the 32-bit 80386 registers, making them unusable by any other program until this was fixed. The problem was noticed by Phil Katz who added a switch to his PKZIP suite of programs to enable 32-bit register use only when the Netware TSRs were not present.
NetWare version 3 eased development and administration by modularization. Each functionality was controlled by a software module called a NetWare Loadable Module (NLM) loaded either at startup or when it was needed. It was then possible to add functionality such as anti-virus software, backup software, database and web servers, long name support (standard filenames were limited to 8 characters plus a three letter extension, matching MS-DOS) or Macintosh style files.
NetWare continued to be administered using console-based utilities. The file system introduced by NetWare 3.x and used by default until NetWare 5.x was NetWare File System 386, or NWFS 386, which significantly extended volume capacity (1 TB, 4 GB files) and could handle up to 16 volume segments spanning multiple physical disk drives. Volume segments could be added while the server was in use and the volume was mounted, allowing a server to be expanded without interruption.
Initially, NetWare used Bindery services for authentication. This was a stand-alone database system where all user access and security data resided individually on each server. When an infrastructure contained more than one server, users had to log-in to each of them individually, and each server had to be configured with the list of all allowed users.
"NetWare Name Services" was a product that allowed user data to be extended across multiple servers, and the Windows "Domain" concept is functionally equivalent to NetWare v3.x Bindery services with NetWare Name Services added on (e.g. a 2-dimensional database, with a flat namespace and a static schema).
For a while, Novell also marketed an OEM version of NetWare 3, called Portable NetWare, together with OEMs such as Hewlett-Packard, DEC and Data General, who ported Novell source code to run on top of their Unix operating systems. Portable NetWare did not sell well.
While Netware 3.x was current, Novell introduced its first high-availability clustering system, named NetWare SFT-III, which allowed a logical server to be completely mirrored to a separate physical machine. Implemented as a shared-nothing cluster, under SFT-III the OS was logically split into an interrupt-driven I/O engine and the event-driven OS core. The I/O engines serialized their interrupts (disk, network etc.) into a combined event stream that was fed to two identical copies of the system engine through a fast (typically 100 Mbit/s) inter-server link. Because of its non-preemptive nature, the OS core, stripped of non-deterministic I/O, behaves deterministically, like a large finite state machine.
The outputs of the two system engines were compared to ensure proper operation, and two copies fed back to the I/O engines. Using the existing SFT-II software RAID functionality present in the core, disks could be mirrored between the two machines without special hardware. The two machines could be separated as far as the server-to-server link would permit. In case of a server or disk failure, the surviving server could take over client sessions transparently after a short pause since it had full state information and did not, for example, have to re-mount the volumes - a process at which NetWare was notoriously slow. SFT-III was the first NetWare version able to make use of SMP hardware - the I/O engine could optionally be run on its own CPU. The modern incarnation of NetWare's clustering, Novell Cluster Services (introduced in NetWare v5.0), is very different from SFT-III. NetWare SFT-III, ahead of its time in several ways, was a mixed success.
NetWare 386 3.x was designed to run all applications on the server at the same level of processor memory protection, known as "ring 0". While this provided the best possible performance, it sacrificed reliability. The result was that crashing (known as abends, short for abnormal ends) were possible and would result in stopping the system. Starting with NetWare 5.x, software modules (NetWare Loadable Modules or NLM's) could be assigned to run in different processor protection rings, ensuring that a software error would not crash the system.
NetWare 4.x
Version 4 in 1993 also introduced NetWare Directory Services, later re-branded as Novell Directory Services (NDS), based on X.500, which replaced the Bindery with a global directory service, in which the infrastructure was described and managed in a single place. Additionally, NDS provided an extensible schema, allowing the introduction of new object types. This allowed a single user authentication to NDS to govern access to any server in the directory tree structure. Users could therefore access network resources no matter on which server they resided, although user license counts were still tied to individual servers. (Large enterprises could opt for a license model giving them essentially unlimited per-server users if they let Novell audit their total user count)
Version 4 also introduced a number of useful tools and features, such as transparent compression at file system level and RSA public/private encryption.
Another new feature was the NetWare Asynchronous Services Interface (NASI). It allowed network sharing of multiple serial devices, such as modems. Client port redirection occurred via an MS-DOS or Microsoft Windows driver allowing companies to consolidate modems and analog phone lines.[2]
Strategic mistakes
Novell's strategy with NetWare 286 2.x and 3.x was very successful; before the arrival of Windows NT Server, Novell claimed 90% of the market for PC based servers.
While the design of NetWare 3.x and later involved a DOS partition to load NetWare server files, this feature became a liability as new users preferred the Windows graphical interface to learning DOS commands necessary to build and control a NetWare server. Novell could have eliminated this technical liability by retaining the design of NetWare 286, which installed the server file into a Novell partition and allowed the server to boot from the Novell partition without creating a bootable DOS partition. Novell finally added support for this in a Support Pack for NetWare 6.5.
As Novell used IPX/SPX instead of TCP/IP, they were poorly positioned to take advantage of the Internet in 1995. This resulted in Novell servers being bypassed for routing and Internet access, in favor of hardware routers, Unix-based operating systems such as FreeBSD, and SOCKS and HTTP Proxy Servers on Windows and other operating systems.[citation needed]
NetWare 4.1x and NetWare for Small Business: Novell begins to recover
Novell priced NetWare 4.10 similarly to NetWare 3.12, allowing customers who resisted NDS (typically small businesses) to try it at no cost.
Later Novell released NetWare version 4.11 in 1996 which included many enhancements that made the operating system easier to install, easier to operate, faster, and more stable. It also included the first full 32-bit client for Microsoft Windows-based workstations, SMP support and the NetWare Administrator (NWADMIN or NWADMN32), a GUI-based administration tool for NetWare. Previous administration tools used the Cworthy interface, the character-based GUI tools such as SYSCON and PCONSOLE with blue text-based background. Some of these tools survive to this day, for instance MONITOR.NLM.
Novell packaged NetWare 4.11 with its Web server, TCP/IP support and Netscape browser into a bundle dubbed IntranetWare (also written as intraNetWare). A version designed for networks of 25 or fewer users was named IntranetWare for Small Business and contained a limited version of NDS and tried to simplify NDS administration. The intranetWare name was dropped in NetWare 5.
During this time Novell also began to leverage its directory service, NDS, by tying their other products into the directory. Their e-mail system, GroupWise, was integrated with NDS, and Novell released many other directory-enabled products such as ZENworks and BorderManager.
NetWare still required IPX/SPX as NCP used it, but Novell started to acknowledge the demand for TCP/IP with NetWare 4.11 by including tools and utilities that made it easier to create intranets and link networks to the Internet. Novell bundled tools, such as the IPX/IP gateway, to ease the connection between IPX workstations and IP networks. It also began integrating Internet technologies and support through features such as a natively hosted web server.
NetWare 5.x
With the release of NetWare 5 in October 1998, Novell finally acknowledged the prominence of the Internet by switching its primary NCP interface from the IPX/SPX network protocol to TCP/IP. IPX/SPX was still supported, but the emphasis shifted to TCP/IP. Novell also added a GUI to NetWare. Other new features were:
• Novell Storage Services (NSS), a new file system to replace the traditional NetWare File System - which was still supported
• Java virtual machine for NetWare
• Novell Distributed Print Services (NDPS)
• ConsoleOne, a new Java-based GUI administration console
• directory-enabled Public key infrastructure services (PKIS)
• directory-enabled DNS and DHCP servers
• support for Storage Area Networks (SANs)
• Novell Cluster Services (NCS)
• Oracle 8i with a 5-user license
The Cluster Services were a major advance over SFT-III, as NCS does not require specialized hardware or identical server configurations.
NetWare 5 was released during a time when NetWare market share dropped precipitously; many companies and organizations were replacing their NetWare servers with servers running Microsoft's Windows NT operating system. Novell also released their last upgrade to the NetWare 4 operating system, NetWare 4.2.
NetWare 5.1 was released in January 2000, shortly after its predecessor. It introduced a number of useful tools, such as:
• IBM WebSphere Application Server
• NetWare Management Portal (later renamed Novell Remote Manager), web-based management of the operating system
• FTP, NNTP and streaming media servers
• NetWare Web Search Server
• WebDAV support
NetWare 6.0
NetWare 6 was released in October 2001. This version has a simplified licensing scheme based on users, not servers. This allows unlimited connections per user.
NetWare 6.5
NetWare 6.5 was released in August 2003. Some of the new features in this version were:
• more open-source products such as PHP, MySQL and OpenSSH
• a port of the Bash shell and a lot of traditional Unix utilities such as wget, grep, awk and sed to provide additional capabilities for scripting
• iSCSI support (both target and initiator)
• Virtual Office - an "out of the box" web portal for end users providing access to e-mail, personal file storage, company address book, etc.
• Domain controller functionality
• Universal password
• DirXML Starter Pack - synchronization of user accounts with another eDirectory tree, a Windows NT domain or Active Directory.
• exteNd Application Server - a J2EE 1.3-compatible application server
• support for customized printer driver profiles and printer usage auditing
• NX bit support
• support for USB storage devices
• support for encrypted volumes
The latest - and apparently last - Service Pack for Netware 6.5 is SP8, released October 2008.
Open Enterprise Server
Main article: Novell Open Enterprise Server
1.0
In 2003, Novell announced the successor product to NetWare: Open Enterprise Server (OES). First released in March 2005, OES completes the separation of the services traditionally associated with NetWare (e.g. Directory Services, file-and-print) from the platform underlying the delivery of those services. OES is essentially a set of applications (eDirectory, NetWare Core Protocol services, iPrint, etc.) that can run atop either a Linux or a NetWare kernel platform. Clustered OES implementations can even migrate services from Linux to NetWare and back again, making Novell one of the very few vendors to offer a multi-platform clustering solution.
Consequent to Novell's acquisitions of Ximian and SuSE, a German Linux distributor, it is widely observed that Novell is moving away from NetWare and shifting its focus towards Linux. Much recent marketing seems to be focussed on getting faithful NetWare users to move to the Linux platform in future releases. The clearest indication of this direction is Novell's controversial decision to release Open Enterprise Server in Linux form only. Novell later watered down this decision and stated that NetWare's 90 million users would be supported until at least 2015. Some of Novell's more perverse NetWare supporters have taken it upon themselves to petition Novell to keep NetWare in development.
2.0
OES 2 was released on October 8, 2007. It includes NetWare 6.5 SP7, which supports running as a paravirtualized guest inside the Xen hypervisor and new Linux based version using SLES10.
New features include
• 64bit support
• Virtualization
• Dynamic Storage Technology, which provide Shadow Volumes
• Domain services for Windows (provided in OES 2 service pack 1)
Current NetWare situation
While Novell NetWare is still used by some organizations, its ongoing decline in popularity began in the mid-1990s, when NetWare was the de facto standard for file and print software for the Intel x86 server platform. Modern (2009) NetWare and OES installations are used by larger organizations that may need the added flexibility they provide.
Microsoft successfully shifted market share away from NetWare products toward their own in the late-1990s. Microsoft's more aggressive marketing was aimed directly to management through major magazines; Novell NetWare's was through IT specialist magazines with distribution limited to select IT personnel.
Novell did not adapt their pricing structure accordingly and NetWare sales suffered at the hands of those corporate decision makers whose valuation was based on initial licensing fees. As a result organizations that still use NetWare, eDirectory, and Novell software often have a hybrid infrastructure of NetWare, Linux, and Windows servers.
Netware Lite / Personal Netware
In 1991 Novell introduced a radically different and cheaper product - Netware Litez in answer to Artisoft's similar LANtastic. Both were peer to peer systems, where no specialist server was required, but instead all PCs on the network could share their resources.
The product line became Personal Netware in 1993.
Performance
NetWare dominated the network operating system (NOS) market from the mid-80s through the mid- to late-90s due to its extremely high performance relative to other NOS technologies. Most benchmarks during this period demonstrated a 5:1 to 10:1 performance advantage over products from Microsoft, Banyan, and others. One noteworthy benchmark NetWare 3.x running NFS services over TCP/IP (not NetWare's native IPX protocol) to a dedicated Auspex NFS server and a SCO Unix server running NFS service. NetWare NFS outperformed both 'native' NFS systems and claimed a 2:1 performance advantage over SCO Unix NFS on the same hardware. There were several reasons for NetWare's performance.
File service instead of disk service
At the time NetWare was first developed, nearly all LAN storage was based on the disk server model. This meant that if a client computer wanted to read a particular block from a particular file it would have to issue the following requests across the relatively slow LAN:
1. Read first block of directory
2. Continue reading subsequent directory blocks until the directory block containing the information on the desired file was found, could be many directory blocks
3. Read through multiple file entry blocks until the block containing the location of the desired file block was found, could be many directory blocks
4. Read the desired data block
NetWare, since it was based on a file service model, interacted with the client at the file API level:
1. Send file open request (if this hadn't already been done)
2. Send a request for the desired data from the file
All of the work of searching the directory to figure out where the desired data was physically located on the disk was performed at high speed locally on the server. By the mid-1980s, most NOS products had shifted from the disk service to the file service model. Today, the disk service model is making a comeback, see SAN.
Aggressive caching
From the start, NetWare was designed to be used on servers with copious amounts of RAM. The entire file allocation table (FAT) was read into RAM when a volume was mounted, thereby requiring a minimum amount of RAM proportional to online disk space; adding a disk to a server would often require a RAM upgrade as well. Unlike most competing network operating systems prior to Windows NT, NetWare automatically used all otherwise unused RAM for caching active files, employing delayed write-backs to facilitate re-ordering of disk requests (elevator seeks). An unexpected shutdown could therefore corrupt data, making an uninterruptible power supply practically a mandatory part of a server installation.
The default dirty cache delay time was fixed at 2.2 seconds in NetWare 286 versions 2.x. Starting with NetWare 386 3.x, the dirty disk cache delay time and dirty directory cache delay time settings controlled the amount of time the server would cache changed ("dirty") data before saving (flushing) the data to a hard drive. The default setting of 3.3 seconds could be decreased to 0.5 seconds but not reduced to zero, while the maximum delay was 10 seconds. The option to increase the cache delay to 10 seconds provided a significant performance boost. Windows 2000 and 2003 server do not allow adjustment to the cache delay time. Instead, they use an algorithm that adjusts cache delay.
Efficiency of NetWare Core Protocol (NCP)
Most network protocols in use at the time NetWare was developed didn't trust the network to deliver messages. A typical client file read would work something like this:
1. Client sends read request to server
2. Server acknowledges request
3. Client acknowledges acknowledgement
4. Server sends requested data to client
5. Client acknowledges data
6. Server acknowledges acknowledgement
In contrast, NCP was based on the idea that networks worked perfectly most of the time, so the reply to a request served as the acknowledgement. Here is an example of a client read request using this model:
1. Client sends read request to server
2. Server sends requested data to client
All requests contained a sequence number, so if the client didn't receive a response within an appropriate amount of time it would re-send the request with the same sequence number. If the server had already processed the request it would resend the cached response, if it had not yet had time to process the request it would only send a "positive acknowledgement". The bottom line to this 'trust the network' approach was a 2/3 reduction in network transactions and the associated latency.

Non-preemptive OS designed for network services
One of the raging debates of the 90s was whether it was more appropriate for network file service to be performed by a software layer running on top of a general purpose operating system, or by a special purpose operating system. NetWare was a special purpose operating system, not a timesharing OS. It was written from the ground up as a platform for client-server processing services. Initially it focused on file and print services, but later demonstrated its flexibility by running database, email, web and other services as well. It also performed efficiently as a router, supporting IPX, TCP/IP, and Appletalk, though it never offered the flexibility of a 'hardware' router.
In 4.x and earlier versions, NetWare did not support preemption, virtual memory, graphical user interfaces, etc. Processes and services running under the NetWare OS were expected to be cooperative, that is to process a request and return control to the OS in a timely fashion. On the down side, this trust of application processes to manage themselves could lead to a misbehaving application bringing down the server.
By comparison, general purpose operating systems such as Unix or Microsoft Windows were based on an interactive, time-sharing model where competing programs would consume all available resources if not held in check by the Operating System. Such environments operated by preemption, memory virtualization, etc., generating significant overhead because there were never enough resources to do everything every application desired. These systems improved over time as network services shed their “application” stigma and moved deeper into the kernel of the “general purpose” OS, but they never equaled the efficiency of NetWare

Probably the single greatest reason for Novell's success during the 80's and 90's was the efficiency of NetWare compared to general purpose operating systems. However, as microprocessors increased in power, efficiency became less and less of an issue. With the introduction of the Pentium processor, NetWare's performance advantage began to be outweighed by the complexity of managing and developing applications for the NetWare environment.[