High performance file system

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Manufacturer Microsoft
Full name High performance file system
Initial release November 1989 ( OS / 2 1.2)
Partition identifier 0x07 ( MBR )
Technical implementation
Directories B + tree
Files B + tree
Defect block list B + tree
Maximum values
Size of a file 2 GiB
Number of all files no limit
Length of the file name 255 characters
File system size 64 GiB
Allowed characters in the file name all non-control characters from UCS-2
Dates of a file Creation, modification, last access
Forks Supported
File attributes Read-only , Hidden, System File, Archive
File rights management unsupported
Transparent compression unsupported
Transparent encryption unsupported
Supporting operating systems OS / 2 , Windows NT , Windows 2000 , Linux

HPFS is the file system of OS / 2 . It was introduced in 1989 with OS / 2 version 1.2 as the first implementation of an installable file system (IFS). In contrast to the FAT16 file system integrated directly in the system kernel , it supports partitions up to a theoretical size of 2 tebibytes (in practice up to 64 gibibytes ) and long file names with up to 255 characters, as well as so-called extended attributes, which allow any meta information with a size of up to 64  KiB per file, to bind to a file without changing its content. So z. B. clearly define the application with which a file can be processed. At the same time, this eliminates the need to give a file a specific file extension (e.g. under Windows ).

The lack of journaling makes the file system vulnerable to crashes. Because of this and the size restrictions for files and partitions, IBM later developed the Journaled File System , which has been supported by OS / 2 since 2000.

HPFS 386

HPFS has been implemented in two flavors in OS / 2. The standard version was included with the operating system, there was also a 32-bit version called HPFS386 , which was part of the LAN server , among other things .

Operating system support


Various programs are available for reading HPFS file systems. Some also offer writing options.

Windows NT

In addition to the NTFS file system, which was new at the time, the first versions of Windows NT also supported HPFS and could be installed on HPFS-formatted IFS partitions if required. Windows NT 4.0 no longer supports HPFS by default unless an update installation of Windows NT 4.0 is performed from an existing Windows NT 3.51 installation. The driver can also be copied and installed manually from the Windows NT 3.51 CD. With Windows 2000 , the necessary driver is available on the Windows 2000 CD and can be installed later if necessary. In all cases, the supplied driver only supports partitions up to a size of 4 GiB, larger partitions are not supported and are destroyed when accessed. In Windows XP, HPFS support has been removed - even a Windows NT operating system installed on an HPFS partition can no longer be started.


A kernel module originally only provided read access. In later versions the writing functionality was added and other extensions made.

See also

Web links

Individual evidence

  1. HPFS despite Windows NT 4.0. ( Memento of March 15, 2008 in the Internet Archive ) c't 4/96, p. 358; online at heise.de
  2. https://www.phoronix.com/scan.php?page=news_item&px=HPFS-FSTRIM-Added