Apple File System
| Developer(s) | Apple Inc. |
|---|---|
| Full name | Apple File System |
| Limits | |
| Max. file size | 263 bytes |
| Max. number of files | 263 |
| Features | |
| Date resolution | Nanosecond |
| Transparent encryption | Yes |
| Copy-on-write | Yes |
| Other | |
| Supported operating systems | macOS, iOS, tvOS, and watchOS |
Apple File System (APFS) is a file system for macOS, iOS, tvOS and watchOS, currently being developed and deployed by Apple Inc. It aims at addressing the core issues of the existing HFS+ file system in use on these platforms today.
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. It was designed to scale from Apple Watch to Mac Pro.
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.
Apple File System supports snapshots for creating a point-in-time, read-only instance of the file system.
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:
Apple File System uses checksums to ensure data integrity for metadata, but not user data.
Apple File System is designed to be crash protected.
Apple File System does not provide checksum for user data, but it does checksum metadata for integrity. Additionally, it does not take advantage of byte-addressable non-volatile random-access memory.
Apple File System is available — but with numerous limitations — in macOS Sierra, and is considered experimental. Among the limitations:
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