Apple is introducing a new file system to replace the twentieth-century HFS+. The new one is called APFS, which simply stands for “Apple File System.” When Apple released HFS+, disk sizes were measured in megabytes, not terabytes.
New features include 64-bit inode numbers, nanosecond timestamp granularity, and native support for encryption. Ars Technica offers a discussion of the system, which is still in an experimental state.
The file system is always case-sensitive. A frustrating feature of OS X is that it’s case-sensitive some of the time and case-insensitive at other times. This can drive users crazy when working at the command line level, where file names that differ only in case may or may not be equivalent. At the Finder level, file names are case-insensitive. Will APFS be more consistent, or will it add to the confusion? We’ll have to wait and see.
A “clone” feature supports efficient versioning. “When a cloned file is modified, only the modified blocks are written to new locations on storage. In this way, the file system can store multiple revisions of the same document with less storage space.”
It will be a while before bootable APFS volumes are available. Hopefully developers of other operating systems will quickly add modules so they can access APFS drives.