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. APFS is the name of the on-disk volume format of the Apple File System.^{[citation needed]}

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 takes advantage of modern hardware with strong checksums and error correction in firmware. To ensure data integrity, Apple File System checksums metadata but not user data.^[3]

See also

• Btrfs
• ReFS
• Write Anywhere File Layout
• ZFS

References

External links

• Apple File System Guide at Apple Developer
• APFS in Detail: Overview