NetWare File System: Difference between revisions

Revision as of 21:14, 27 July 2010

Revision as of 21:37, 27 July 2010

Line 5:

| introduction_date =

| introduction_os =

| partition_id = 0x64 (2.x), 0x65 (3.X-6.X)

| directory_struct = 32 bit Mirrored FAT

| file_struct = 64K Indexed Block

| bad_blocks_struct = Hotfixing

| max_file_size = 4 [[Gibibyte|GiB]] x 64K

| max_files_no = 4 Billion

| max_filename_size = 256 bytes

| max_volume_size = 161 [[Tebibyte|TiB]]

| dates_recorded =

| date_range =

Line 19:

| attributes =

| file_system_permissions =

| compression = Yes (Shannon Fano)

| encryption = Yes

| OS = [[Novell NetWare]],[[Linux]],[[Windows]]

}}

'''NetWare File System''' ('''NWFS''') is a [[file system]], based on a heavily-modified version of [[File Allocation Table|FAT]]. It was used in the [[Novell NetWare]] [[operating system]]. It is the default and only file system for all volumes in versions 2.x through 4.x, and the default and only file system for the SYS volume continuing through version 5.x. There were two varieties of NWFS: 16-bit NWFS 286, used in NetWare 2.x; and 32-bit NWFS 386, used in NetWare 3.x through NetWare 6.x. It was superseded by the release of [[Novell Storage Services]] (NSS) in 1998.

The NWFS on-disk format was never publicly documented by Novell. The published specifications for 32-bit NWFS are:

'''NetWare File System''' ('''NWFS''') is a [[file system]], based on a heavily-modified version of [[File Allocation Table|FAT]]. It was used in the [[Novell NetWare]] [[operating system]]. It is the default and only file system for all volumes in versions 2.x through 4.x, and the default and only file system for the SYS volume continuing through version 5.x. There were two varieties of NWFS: 16-bit NWFS 286, used in NetWare 2.x; and 32-bit NWFS 386, used in NetWare 3.x through NetWare 6.x. It was superseded by the release of [[Novell Storage Services]] (NSS) in 1998.

* Maximum volumefile size: 16TB4GB

* Maximum filevolume size: 4 billion x 64K1TB

The Netware File System uses a 32 bit File Allocation Table scheme similar to the MSDOS file system with several improvements including block suballocation, sparse files by the use of block indexes in the fat tables, and mirrored fat and directory files. The NetWare file system also employed a 4 way cylinder aligned segment table to record volume disk segments should a drive spindle fail allowing recovery. NSS subsequently integrated many of the robust features of the NetWare File system into its design including mirroring and hotfixing. The Open Source NetWare File System was designed by Jeff Merkey and Darren Major.

* Maximum files per volume: 42 billionmillion when using a single name space.

* Maximum files per server: 416 Billionmillion

The NetWare file system was the first storage architecture to employ sector remapping for failed drive sectors called drive hotfixing which would redirect sector mapping to a reserved area of the device. Later Disk Drive manufactuters employed the same technique internally within the drive logic to perform a similar function transparently to the host operating system.

* Maximum directory entries: 416 Billionmillion

== Open Source NetWare File System ==

In 1999 the Open Source NetWare File System was released on Linux and Windows. The NWFS on-disk format for NetWare 3.x, 4,x, and 5.x was developed and then publicly released on Linux in 1999 and 2000 by former Novell Chief Scientist Jeff Merkey and Darren Major from the Timpanogas Research Group. The specifications for 32-bit NWFS was never published by Novell but the open source version published disclosed the actual specifications for NWFS:

* Maximum file size: 4 billion x 64K

* Maximum volume size: 16TB

* Maximum files per volume: 4 billion when using a single name space.

* Maximum files per server: 4 Billion

* Maximum directory entries: 4 Billion

* Directory Record Size: 128 bytes (DOS), 3 x 128 (LONGNAME), 3 x 128 (UNIX), 2 x 128 (MAC)

* Maximum volumes per server: 64

* Maximum volumes per partition: 8

* Maximum open files per server: 100,000

* Maximum directory tree depth: Infinite100 levels

* Characters used: ASCII double-byte, [[UTF8]]

* Maximum [[Metadata_(computing)|extended attributes]]: 16

* Maximum [[Fork (filesystem)|data streams]]: 10

Line 54 ⟶ 45:

Transparent file compression was also supported, although this had a significant impact on the performance of file serving.

Every name space requires its own separate directory entry for each file. While Thethe FTAMmaximum namespacenumber wasof laterdirectory convertedentries intois a16,000,000, B++two treeresident forname journalledspaces recoverywould asreduce thisthe namespaceusable wasmaximum reservednumber butof neverdirectory usedentries into practice8,000,000, and three to 5,333,333.

16-bit NWFS could handle volumes of up to 256MB. However, its only name space support was a dedicated [[Application programming interface|API]] to handle Macintosh clients.

== See also ==

{{Portal|Free software}}

* [[List of file systems]]

* [[Comparison of file systems]]

Line 66 ⟶ 57:

* [http://www.novell.com/documentation/nw51/index.html?page=/documentation/nw51/nss__enu/data/hn0r5fzo.html Comparison of NW file systems]

* [http://www.novell.com/documentation/nw51/nss__enu/data/h5grftdf.html Another specification comparison page]

* [http://nwfs.googlecode.com Open Source NetWare File System]

{{Compu-storage-stub}}