HFS+ Filesystem

HFS+ is a file system developed by Apple, first released in 1998 with Mac OS X Server.

Key Features:

  1. Journaling: HFS+ uses journaling to ensure data integrity and prevent corruption in case of system crashes or power failures.
  2. Forks: HFS+ supports forks, which allow a file to have multiple streams of data associated with it.
  3. Attributes: HFS+ supports file attributes, such as permissions, ownership, and access control lists (ACLs).
  4. Unicode support: HFS+ supports Unicode character encoding, allowing for internationalization and localization.

Benefits:

  1. Improved reliability: Journaling ensures that data is safely stored and can be recovered in case of a system crash.
  2. Increased flexibility: Forks allow developers to associate multiple streams of data with a single file.
  3. Enhanced security: Attributes provide an additional layer of access control, ensuring that sensitive data is protected.

Technical Details:

  1. Block size: HFS+ uses a block size of 512 bytes or 4KB.
  2. File system layout: The HFS+ file system is laid out in a hierarchical structure, with directories and files stored in a tree-like fashion.
  3. Metadata management: Metadata, such as file attributes and ownership information, is managed by the HFS+ file system.

History:

  1. Release: HFS+ was first released in 1998 with Mac OS X Server.
  2. Evolution: Over the years, HFS+ has undergone several revisions and improvements, including support for larger volumes, improved performance, and enhanced security features.
  3. Replacement: In 2017, Apple announced that it would be replacing HFS+ with a new file system called APFS (Apple File System).

APFS vs HFS+:

  1. Performance: APFS offers improved performance and responsiveness compared to HFS+.
  2. Security: APFS provides enhanced security features, such as built-in encryption and access control lists.
  3. Compatibility: APFS is designed to be compatible with existing HFS+ file systems, ensuring a smooth transition.

Legacy Support:

  1. Mac OS X 10.12 and earlier: These versions of Mac OS X still use HFS+ as the default file system.
  2. Boot volumes: Some boot volumes may still use HFS+, although APFS is recommended for new installations.
  3. Third-party software: Some third-party software applications may still require HFS+ support.

In summary, HFS+ is a robust and feature-rich file system developed by Apple, offering journaling, forks, attributes, and Unicode support. While it has been largely replaced by APFS, HFS+ remains in use on legacy systems and certain boot volumes, ensuring compatibility and continued support for existing applications and workflows.