HFS+

HFS+

HFS+ (Hierarchical File System Plus) is a file system developed by Apple Inc. for use in macOS and other Apple operating systems. It is an evolution of the earlier HFS (Hierarchical File System) and was introduced in 1998 with the release of Mac OS 8.1.

History

HFS+ was designed to address the limitations of the original HFS, which was introduced in 1985. The primary motivation for developing HFS+ was to support larger file sizes and volumes, as well as to improve performance and efficiency on modern storage devices.

Technical Features

HFS+ includes several enhancements over its predecessor:

• Larger File and Volume Sizes: HFS+ supports files up to 8 exabytes in size and volumes up to 8 exabytes, compared to the 2 GB file size limit and 2 TB volume size limit of HFS.

• Unicode Support: HFS+ uses Unicode for file and directory names, allowing for a wider range of characters and internationalization.

• Efficient Storage: HFS+ uses a more efficient method of storing file metadata, reducing the amount of space required for file system overhead.

• Journaling: Introduced in later versions, HFS+ supports journaling, which helps protect the file system against corruption in the event of a crash or power failure.

• Hard Links and Aliases: HFS+ supports hard links and aliases, providing more flexibility in file management.

Usage

HFS+ was the default file system for macOS until the introduction of APFS (Apple File System) in 2017 with macOS High Sierra. Despite being replaced by APFS, HFS+ remains in use for certain applications and compatibility purposes.

Limitations

While HFS+ was a significant improvement over HFS, it has several limitations compared to modern file systems:

• Fragmentation: HFS+ can suffer from fragmentation over time, which can degrade performance.

• Lack of Checksums: HFS+ does not include checksums for data integrity, making it less robust against data corruption compared to newer file systems like APFS.

• Limited Support for Modern Features: HFS+ lacks support for features such as snapshots and native encryption, which are available in APFS.

Transition to APFS

With the release of macOS High Sierra, Apple introduced APFS as the new default file system for macOS. APFS offers several advantages over HFS+, including improved performance, better support for SSDs, and advanced features like snapshots and encryption.

See Also

• APFS
• File System
• macOS

References

• Apple Developer Documentation on HFS+
• "Inside Macintosh: Files" by Apple Inc.