HFS Plus

HFS+
Developer(s)	Apple Inc.
Full name	Hierarchical File System Plus
Introduced	January 19, 1998 with Mac OS 8.1
Preceded by	HFS
Succeeded by	APFS
Partition IDs	Apple_HFS (Apple Partition Map)0xAF (MBR) HFS and HFS+Apple_HFSX (Apple Partition Map) when HFSX ; 48465300-0000-11AA-; AA11-00306543ECAC (GPT)
Structures
Directory contents	B-tree
File allocation	Bitmap
Bad blocks	B-tree
Limits
Max volume size	8 exabyte
Max file size	8 EB
Max no. of files	4,294,967,295 (232 − 1)
Max filename length	255 characters (255 UTF-16 encoding units, normalized to Apple-modified variant of Unicode Normalization Format D)
Allowed filename; characters	Unicode, any character, including NUL. OS APIs may limit some characters for legacy reasons
Features
Dates recorded	access, attributes modified, backed up, contents modified, created
Date range	January 1, 1904 – February 6, 2040
Date resolution	1 s
Forks	Yes
Attributes	Color (3 bits, all other flags 1 bit), locked, custom icon, bundle, invisible, alias, system, stationery, inited, no INIT resources, shared, desktop
File system; permissions	Unix permissions, NFSv4 ACLs (Mac OS X v10.4 onward)
Transparent; compression	Partial (decmpfs, on Mac OS X 10.6 and higher)
Transparent; encryption	Yes (on Mac OS X 10.7 and up). Per-home directory encryption is available with AES[clarification needed] using HFS+-formatted .dmg volumes on OS X versions prior to 10.7 but later than Mac OS X 10.3
Other
Supported; operating systems	Mac OS 8.1, Mac OS 9, macOS/iOS/tvOS/watchOS/Darwin, Linux, Microsoft Windows (through Boot Camp IFS drivers)

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.

^ "OS X: Mac OS Extended format (HFS Plus) volume and file limits". Support.apple.com. 2008-07-29. Archived from the original on 2010-07-30. Retrieved 2010-07-05.
^ Cite error: The named reference tn1150 was invoked but never defined (see the help page).
^ "HFS Plus Dates". HFS Plus Volume Format. Apple Inc. March 5, 2004. Technical Note TN1150.
^ "10.6: Compress files with HFS+ compression – Mac OS X Hints". Archived from the original on 2012-04-01.

[1] "OS X: Mac OS Extended format (HFS Plus) volume and file limits". Support.apple.com. 2008-07-29. Archived from the original on 2010-07-30. Retrieved 2010-07-05.

[tn1150-2] Cite error: The named reference tn1150 was invoked but never defined (see the help page).

[3] "HFS Plus Dates". HFS Plus Volume Format. Apple Inc. March 5, 2004. Technical Note TN1150.

[4] "10.6: Compress files with HFS+ compression – Mac OS X Hints". Archived from the original on 2012-04-01.

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