High Performance File System: Difference between revisions

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{{Short description|Filesystem created for OS/2 operating system}}

{{infobox filesystem |

{{distinguish|Hi Performance FileSystem}}

name = HPFS |

{{ref improve|date=August 2013}}

full_name = High Performance File System |

{{infobox filesystem

developer = [[Microsoft]] |

|name = HPFS

introduction_os = [[OS/2]] 1.2|

|full_name = High Performance File System

introduction_date = November 1989 |

|developer = [[Microsoft]], [[IBM]]

partition_id = 0x07 ([[MBR]]) |

|introduction_os = [[OS/2 1.2]]

directory_struct = [[B_plus_tree|B+Tree]] |

|introduction_date = {{Start date and age|1989|11}}

file_struct = [[B_plus_tree|B+Tree]] |

|partition_id = <code>[[Partition type#PID_07h|0x07]]</code> ([[Master Boot Record|MBR]])

bad_blocks_struct = [[B_plus_tree|B+Tree]] |

|directory_struct = [[B tree]]

max_filename_size = 255 characters |

|file_struct = [[B+ tree]]

max_files_no = Unlimited |

|bad_blocks_struct = [[List (abstract data type)|List]]

max_volume_size = 2 [[tebibyte|TiB]] |

|max_filename_size = 255 characters

max_file_size = 2 [[gigibyte|GiB]] |

|max_files_no = Unlimited

filename_character_set = Double-byte from 0x0020 to 0xFFFF |

|max_volume_size = 64 [[gigabyte|GB]] (as implemented)<br/>2 [[terabyte|TB]] (theoretical)

dates_recorded = Access, Creation, Modified |

| max_file_size = 2 [[gigabyte|GB]]

date_range = Unknown |

|filename_character_set = Single-byte from <code>0x20</code> to <code>0xFF</code>

forks_streams = Yes |

|dates_recorded = Access, Creation, Modified

attributes = Read-only, hidden, system, archive |

|date_range =

file_system_permissions = Yes (only in HPFS386) |

|date_resolution =

compression = No |

|forks_streams = Yes

encryption = No |

|attributes = Read-only, hidden, system, archive

|file_system_permissions = Yes (only in HPFS386)

|compression = No

|encryption = No

|OS = [[OS/2]], [[Windows NT]], [[Linux]], [[DragonFly BSD]], [[eComStation]], [[ArcaOS]]

}}

'''HPFS''' or ('''High Performance File System''',) is a [[file system]] created specifically for the [[OS/2]] [[operating system]] to improve upon the limitations of the [[File Allocation Table|FAT]] file system. It was written by [[Gordon Letwin]] and others at [[Microsoft]] and added to OS/2 version [[OS/2 1.2|1.2]], at that time still a joint undertaking of Microsoft and [[International Business Machines|IBM]], and released in 1988.

== Overview ==

Among its improvements are

Compared with FAT, HPFS provided a number of additional capabilities:

* support for [[mixed case]] file names, in different code pages;

*Support for [[Case Sensitivity|mixed case]] file names, in different [[code page]]s

* support for long file names (256 characters as opposed to FAT's 11 characters);

*Support for long file names (255 characters as opposed to FAT's [[8.3]] naming scheme)

* more efficient use of disk space (files are not stored using multiple-sector clusters but on a per-sector basis);

*More efficient use of disk space (files are not stored using multiple-sector clusters but on a per-sector basis)

* an internal architecture that keeps related items close to each other on the disk volume;

*An internal architecture that keeps related items close to each other on the disk volume

* less [[fragmentation]] of data;

*Less [[file system fragmentation|fragmentation]] of data

* extent-based space allocation;

*[[Extent (file systems)|Extent]]-based space allocation

* separate datestamps for last modification, last access, and creation (as opposed to FAT's one last modification datestamp);

*Separate datestamps for last modification, last access, and creation (as opposed to last-modification-only datestamp in then-times implementations of FAT)

* a [[b-tree]] structure for directories; and

*[[B+ tree]] structure for directories

* root directory located at the mid-point, rather than beginning of the disk, for faster average access.

*Root directory located at the midpoint, rather than at the beginning of the disk, for faster average access

ItHPFS also can keep 64 [[KibibyteKilobyte|KiBKB]] of [[Metadata (computing)|metadata]] ("Extended[[extended attributesattribute]]s") per file.

IBM offers two kindkinds of [[Installable File System|IFS]] drivers for this file system: the standard one with a cache limited to 2&nbsp;MiB, and HPFS386 provided with the server versions of OS/2. HPFS386's cache is limited by the available memory. It's highly tunable by experienced administrators. Thus, HPFS386 is faster, but IBM is required to pay Microsoft for each copy sold.

*The standard one with a cache limited to 2&nbsp;MB

Because of the Microsoft dependence and the longer disk check times after a crash, IBM ported the [[journaling file system]] [[JFS]] to OS/2 as a substitute.

*''HPFS386'' provided with certain server versions of OS/2, or as added component for the server versions that did not come with it

HPFS386's cache is limited by the amount of available memory in OS/2's system memory arena<ref>{{cite web|title=Virtual Memory Problems under OS/2|url=http://www.os2voice.org/VNL/past_issues/VNL0708H/feature_3.html|publisher=www.os2voice.org|access-date=11 June 2015|archive-url=https://web.archive.org/web/20150924061927/http://www.os2voice.org/VNL/past_issues/VNL0708H/feature_3.html|archive-date=24 September 2015|url-status=dead}}</ref> and was implemented in 32-bit [[assembly language]]. HPFS386 is a [[Ring (computer security)|ring 0]] driver (allowing direct hardware access and direct interaction with the kernel) with built-in SMB networking properties that are usable by various server [[daemon (computing)|daemon]]s, whereas HPFS is a [[Ring 3 (computer security)|ring 3]] driver. Thus, HPFS386 is faster than HPFS and highly optimized for server applications. It is also highly tunable by experienced administrators.

There are also third-party drivers for DOS and Linux and official ones for [[Windows NT]].

Though IBM still had rights to HPFS, its agreement with Microsoft to continue licensing the HPFS386 version was contingent upon the company paying Microsoft a licensing fee for each copy sold. This was a result of the Microsoft and IBM collaboration that gave both the right to use Windows and OS/2 technology.

Due to the Microsoft dependence, limited partition size, file size limit of 2&nbsp;GB and the long disk-check times after a crash, IBM ported the [[journaling file system]], [[JFS (file system)|JFS]], to OS/2 as a substitute.

[[DOS]] and [[Linux]] support HPFS via third-party drivers. [[Windows NT]] versions 3.51 and earlier had native support for HPFS.

== Native support under Windows ==

[[Windows 95]] and its successors [[Windows 98]] and [[Windows Me]] have no support for HPFS. {{citation needed span|date=May 2023|They listed the [[NTFS]] partitions of networked computers as "HPFS"}}, because NTFS and HPFS share the same [[Partition type|filesystem identification number]] in the partition table.

[[Windows NT 3.1]] and [[Windows NT 3.5|3.5]] have native read/write support for local disks and can even be installed onto an HPFS partition.

[[Windows NT 3.51]] can also read and write from local HPFS formatted drives. Starting with [[Windows NT 4]] the filesystem driver ''PINBALL.SYS'' enabling the read/write access is not shipped anymore. Later Windows versions do not ship with this driver. Note that this driver is limited to 4GB HPFS volumes.

Microsoft retained rights to OS/2 technologies, including the HPFS filesystem, after they ceased collaboration with IBM. Since Windows NT 3.1 was designed for more rigorous (enterprise-class) use than previous versions of Windows, it included support for HPFS (and NTFS) giving it a larger storage capacity than the [[FAT12]] and [[FAT16]] filesystems. However, since HPFS lacks a [[Journaling file system|journal]], any recovery after an unexpected shutdown or other error state takes progressively longer as the filesystem grows. A utility such as [[CHKDSK]] would need to scan each entry in the filesystem to ensure no errors are present, a problem which is vastly reduced on NTFS, which simply replays the journal.

== See also ==

* [[Comparison of file systems]]

* [[HPFS BPB]]

==References==

{{reflist}}

== Further reading ==

* {{journalcite referencejournal

| URLurl = http://wwwpages.2kacs.miptwisc.ruedu/~alexpbolo/docs/programming/formatsshipyard/hpfs.pdfhtml

| Titletitle=Design goals and implementation of the new High Performance File System

| Authorauthor=RoyRay Duncan

| Journaljournal=Microsoft Systems Journal

| Yeardate=September 1989|Volumevolume=4:5

| Pagesissue=1–135

| pages=1–13

}}

* {{citenewsauthorcite magazine

| url=http://www.edm2.com/0410/hpfs1.html<!-- http://www.nondot.org/sabre/os/files/FileSystems/HPFS/ -->

| title=Inside the High Performance File SytemSystem - parts 1 to 6

| givenfirst=Dan

| surnamelast=Bridges

| magazine=Electronic Developer Magazine for OS/2

| org=Significant Bits magazine

| date=November 1996

| volume=4

| issue=10

| access-date=2016-07-18

}}

* {{cite journal

| url = http://www.heise.de/ct/97/01/306/

| title=HPFS unter Windows NT 4.0

| author=Dieter Brors

| journal=C't Magazin für Computertechnik (German)

| year=1997|volume=1

| pages=306

}}

* {{cite web

|url=http://www.warpspeed.com.au./Products/OS2/GU/Manual/appg.htm

|title=Appendix G &mdash; HPFS internals

|author=Chris Graham

|work=The Graham Utilities for OS/2 - Version 2

|url-status=dead

|archive-url=https://web.archive.org/web/20060210154146/http://www.warpspeed.com.au/Products/OS2/GU/Manual/appg.htm

|archive-date=2006-02-10

}}

* [https://archive.today/20130130020814/http://homepage2.nifty.com/bayer/hpfs_w2k.html%23English How to get Windows NT 4, Windows 2000, and Windows XP to read HPFS partitions]

{{Filesystem}}

[[Category:Disk file systems]]

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