[9][10] It aims to fix core problems of HFS+ (also called Mac OS Extended), APFS's predecessor on these operating systems.
APFS is optimized for solid-state drive storage and supports encryption, snapshots, and increased data integrity, among other capabilities.
Clones allow the operating system to make efficient file copies on the same volume without occupying additional storage space.
Changes to a cloned file are saved as delta extents, reducing storage space required for document revisions and copies.
APFS volumes support snapshots for creating a point-in-time, read-only instance of the file system.
[16] APFS supports transparent compression on individual files using Deflate (Zlib), LZVN (libFastCompression), and LZFSE.
This feature is inherited from HFS+, and is implemented with the same AppleFSCompression / decmpfs system using resource forks or extended attributes.
[20][21] Enumerating files, and any inode metadata in general, is much slower on APFS when it is located on a hard disk drive.
This fragmentation of metadata means more seeks are performed when listing files, acceptable for SSDs but not HDDs.
[36] Users can disable APFS conversion by using the installer's startosinstall utility on the command line and passing --converttoapfs NO.
[citation needed] iOS 10.3, tvOS 10.2, and watchOS 3.2 convert the existing HFSX file system to APFS on compatible devices.
[40] Competing products, including MicroMat's TechTool and Prosoft's Drive Genius, are expected to increase APFS support as well.
[41] An independent read-only open source implementation by Joachim Metz, libfsapfs, is released under GNU Lesser General Public License v3.