New Apple File System debuts in Sierra, designed for modern media

New APFS file system ups ante in encryption debate

Embedded in the developer preview of macOS Sierra, Apple has included an entirely new file system. Dubbed the "Apple File System," (APFS) the developers' preliminary documentation says that it "is a new, modern file system for iOS, OS X, tvOS and watchOS. It is optimized for Flash/SSD storage and features strong encryption, copy-on-write metadata, space sharing, cloning for files and directories, snapshots, fast directory sizing, atomic safe-save primitives, and improved file system fundamentals."

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.

14 Comments
  1. Avatar
    P Moderator
    Joined: Apr 07, 2000

    64-bit inode numbers, the encryption stuff, copy-on-write, snapshots. Basically it is the bare minimum you need to do to update HFS+ to a modern design, but I can see why they did it that way. ZFS is never going to run on a watch.

  2. Avatar
    coffeetime Grizzled Veteran Joined: Nov 15, 2006

    What? Filenames are case-sensitive only? Would that mess up the search?

  3. Avatar
    Mike Wuerthele Managing Editor Joined: Jul 19, 2012

    Originally Posted by coffeetimeView Post

    What? Filenames are case-sensitive only? Would that mess up the search?



    Much existing software now refuses installation on an OS X volume formatted to be case-sensitive.

  4. Avatar
    farhadd Fresh-Faced Recruit Joined: Oct 28, 2008

    "APFS formatted volumes are not recognized on OS X 10.11 Yosemite and earlier"

    Do you mean 10.10? Or El Capitan?

  5. Avatar
    P Moderator
    Joined: Apr 07, 2000

    Originally Posted by coffeetimeView Post

    What? Filenames are case-sensitive only? Would that mess up the search?



    That is a beta note, from the wording it seems that the release version of the OS will support case insensitive.

    Originally Posted by farhaddView Post

    "APFS formatted volumes are not recognized on OS X 10.11 Yosemite and earlier"

    Do you mean 10.10? Or El Capitan?



    Ask Apple, the error is a direct quote from them. Probably 10.11 El Capitan.

  6. Avatar
    Mike Wuerthele Managing Editor Joined: Jul 19, 2012

    Made a call, got some clarification.

  7. Avatar
    chimaera Dedicated MacNNer Joined: Apr 08, 2007

    The key feature I want in the next file system is file checksums. So you can detect bitrot and let Time Machine correct it in the background - assuming you have an undamaged copy of course. But I've yet to hear any reference to checksums in APFS. It better not be reserved for APFS+ in 2030.

  8. Avatar
    bobolicious Mac Enthusiast Joined: Aug 15, 2002

    ...while the features sound impressive, this sounds like a potentiallychallenging transition... Again. Does this suggest getting any new hardware prior while one still can...?

    I understand W7pro apparently has extended support through 2020, for those that need legacy compatibility & workflow stability... Let the flames begin...

  9. Avatar
    Mike Wuerthele Managing Editor Joined: Jul 19, 2012

    I don't think the transition is going to be that challenging. The OS will still support HFS+ for a while. When it STOPS supporting HFS+? That'll be the challenge.

  10. Avatar
    Inkling Grizzled Veteran Joined: Jul 25, 2006

    I write books that get published, hence nothing I do is secret. Giant corporations, on the other hand, like some politicians (cough, Hill..., cough) have much in their email and internal communications to hide from the law. Hence this great zeal to encrypt, encrypt, encrypt. The bad news is that we honest people are going to be caught up in the complexities created by those obsessed with concealing their schemes.

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