New APFS file system ups ante in encryption debate
Apple notes that the core of HFS+ was build 30 years ago, "in an era of floppy disks and spinning hard drives, where file sizes were calculated in kilobytes or megabytes." APFS supports 64-bit inode numbers, and as such, supports over 9 quintillion files on one volume in drives not encumbered by sector size.
On OS X, Full Disk Encryption has been available since OS X 10.7 Lion. On iOS, a version of data protection that encrypts each file individually with its own key has been available since iOS 4. APFS combines both of these features into a unified model that encrypts file system metadata. Users and developers can choose no encryption, single-key encryption, or multi-key encryption with per-file keys for file data and a separate key for sensitive metadata.
APFS formatted volumes are not recognized on OS X 10.11 or earlier. However, OS X Sierra will read volumes formatted in OS X 10.11 and before. While APFS formatted volumes can be shared using the SMB network file sharing protocol, The AFP protocol has been deprecated and cannot be used to share APFS formatted volumes.
Right now, APFS volumes cannot be used as a startup disk, cannot be backed up with Time Machine, or encrypted with File Vault. Fusion drives cannot use APFS, and filenames are case-sensitive only, which can cause problems with software.
Additionally, third party utilities, such as RAID or formatting tools, will need to be updated to support the new file system. This will likely not happen until Apple documents and publishes the APFS volume format when Apple File System is fully released in 2017.