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Hub AI
HFS Plus AI simulator
(@HFS Plus_simulator)
Hub AI
HFS Plus AI simulator
(@HFS Plus_simulator)
HFS Plus
HFS Plus or HFS+ (also known as Mac OS Extended or HFS Extended) is a journaling file system developed by Apple Inc. It replaced the Hierarchical File System (HFS) as the primary file system of Apple computers with the 1998 release of Mac OS 8.1. HFS+ continued as the primary Mac OS X file system until it was itself replaced with the Apple File System (APFS), released with macOS High Sierra in 2017. HFS+ is also one of the formats supported by the iPod digital music player.
Compared to its predecessor HFS, also called Mac OS Standard or HFS Standard, HFS Plus supports much larger files (block addresses are 32-bit length instead of 16-bit) and using Unicode (instead of Mac OS Roman or any of several other character sets) for naming items. Like HFS, HFS Plus uses B-trees to store most volume metadata, but unlike most file systems that support hard links, HFS Plus supports hard links to directories. HFS Plus permits filenames up to 255 characters in length, and n-forked files similar to NTFS, though until 2005 almost no system software took advantage of forks other than the data fork and resource fork. HFS Plus also uses a full 32-bit allocation mapping table rather than HFS's 16 bits, improving the use of space on large disks.
Codenamed Sequoia in development, HFS+ was introduced with the January 19, 1998, release of Mac OS 8.1.
With the release of the Mac OS X 10.2.2 update on November 11, 2002, Apple added optional journaling features to HFS Plus for improved data reliability. These features were accessible through the GUI, using the Disk Utility application in Mac OS X Server, but only accessible through the command line in the standard desktop client.
With Mac OS X v10.3, all HFS Plus volumes on all Macs were set to be journaled by default. Within the system, an HFS Plus volume with a journal is identified as HFSJ.
Mac OS X 10.3 also introduced another version of HFS Plus called HFSX. HFSX volumes are almost identical to HFS Plus volumes, except that they are never surrounded by the HFS Wrapper that is typical of HFS Plus volumes and they optionally support case sensitivity for file and folder names. HFSX volumes can be recognized by two entries in the Volume Header, a value of HX in the signature field and 5 in the version field.
Mac OS X 10.3 also marked Apple's adoption of Unicode 3.2 decomposition, superseding the Unicode 2.1 decomposition used previously. This change caused problems for developers writing software for Mac OS X.
Mac OS X 10.3 introduced a number of techniques that are intended to avoid fragmentating files in HFS+.
HFS Plus
HFS Plus or HFS+ (also known as Mac OS Extended or HFS Extended) is a journaling file system developed by Apple Inc. It replaced the Hierarchical File System (HFS) as the primary file system of Apple computers with the 1998 release of Mac OS 8.1. HFS+ continued as the primary Mac OS X file system until it was itself replaced with the Apple File System (APFS), released with macOS High Sierra in 2017. HFS+ is also one of the formats supported by the iPod digital music player.
Compared to its predecessor HFS, also called Mac OS Standard or HFS Standard, HFS Plus supports much larger files (block addresses are 32-bit length instead of 16-bit) and using Unicode (instead of Mac OS Roman or any of several other character sets) for naming items. Like HFS, HFS Plus uses B-trees to store most volume metadata, but unlike most file systems that support hard links, HFS Plus supports hard links to directories. HFS Plus permits filenames up to 255 characters in length, and n-forked files similar to NTFS, though until 2005 almost no system software took advantage of forks other than the data fork and resource fork. HFS Plus also uses a full 32-bit allocation mapping table rather than HFS's 16 bits, improving the use of space on large disks.
Codenamed Sequoia in development, HFS+ was introduced with the January 19, 1998, release of Mac OS 8.1.
With the release of the Mac OS X 10.2.2 update on November 11, 2002, Apple added optional journaling features to HFS Plus for improved data reliability. These features were accessible through the GUI, using the Disk Utility application in Mac OS X Server, but only accessible through the command line in the standard desktop client.
With Mac OS X v10.3, all HFS Plus volumes on all Macs were set to be journaled by default. Within the system, an HFS Plus volume with a journal is identified as HFSJ.
Mac OS X 10.3 also introduced another version of HFS Plus called HFSX. HFSX volumes are almost identical to HFS Plus volumes, except that they are never surrounded by the HFS Wrapper that is typical of HFS Plus volumes and they optionally support case sensitivity for file and folder names. HFSX volumes can be recognized by two entries in the Volume Header, a value of HX in the signature field and 5 in the version field.
Mac OS X 10.3 also marked Apple's adoption of Unicode 3.2 decomposition, superseding the Unicode 2.1 decomposition used previously. This change caused problems for developers writing software for Mac OS X.
Mac OS X 10.3 introduced a number of techniques that are intended to avoid fragmentating files in HFS+.