Apple File System

Not to be confused with Apple File Service (AFS), the service implementing the Apple Filing Protocol (AFP), formerly AppleTalk Filing Protocol.

The Apple File System (APFS) is a file system for macOS, iOS, tvOS and watchOS, currently being developed and deployed by Apple Inc.[1][2] It aims at addressing the core issues of the existing HFS+ file system in use on these platforms today.

Overview

Apple File System is optimized for Flash and solid-state drive storage and features a copy-on-write design that uses I/O coalescing for improved performance.

Features

Clones

Clones allow the OS to make fast, power-efficient file copies on the same volume without occupying additional storage space. Modifications to the data write the new data elsewhere and continue to share the unmodified blocks. Changes to a file are saved as differences of the cloned file, reducing storage space required for document revisions and copies.[2]

Snapshots

Apple File System supports snapshots for creating a point-in-time, read-only instance of the file system.[2]

Encryption

Apple File System will implement disk encryption for files and sensitive metadata. It will support the following encryption models for each volume in a container:

  • no encryption,
  • single-key encryption, and
  • multi-key encryption, which encrypts each file with a separate key, with metadata encrypted with another one.[2]

Data integrity

Apple File System uses checksums to ensure data integrity for metadata, but not user data.[3]

Limitations

Apple File System does not provide checksum for user data, but it does checksum metadata for integrity.[4] Additionally, it does not take advantage of byte-addressable non-volatile random-access memory.[5]

Support

Apple File System is available — but with numerous limitations — in macOS Sierra, and is considered experimental. Among the limitations:[6]

  • Drives formatted with Sierra's version of APFS may not be compatible with future versions of macOS nor the final version of APFS
  • There is currently no supported way to convert an HFS+ volume to APFS
  • The only option currently available for APFS is a case sensitive filesystem
  • APFS cannot be used with Time Machine, FileVault encryption, or Fusion drives

A drive partition can be formatted with APFS in macOS Sierra with the diskutil command line utility. A final version is expected in 2017.[6]

See also

References

  1. ^ Roger Fingas (June 13, 2016). "'Apple File System' will scale from Apple Watch to Macs, replace HFS+". Apple Insider. 
  2. ^ a b c d Hutchinson, Lee (13 June 2016). "Digging into APFS, Apple's new file system". Ars Technica UK. Retrieved 15 June 2016. 
  3. ^ Adam Leventhal (June 19, 2016). "APFS in Detail: Data Integrity". 
  4. ^ A ZFS developer’s analysis of the good and bad in Apple’s new APFS file system
  5. ^ Why Apple's APFS won't last 30 years
  6. ^ a b "How to Format a Drive With the APFS File System on macOS Sierra". Retrieved 2016-10-26. 

External links