APFS & spinning externals

Discussion in 'macOS Mojave (10.14)' started by Porkchop Sandwich, Oct 28, 2018.

  1. Porkchop Sandwich macrumors regular

    Feb 3, 2017
    I'm slowly moving all of my computers over to Mojave, with exception of one that'll remain running on HS. Therefore, I'll be updating to APFS on the lions-share of my various computer goods. This includes a few spinning externals that'll be used for TM backups and also simple data storage.

    I'm set to begin the process and I intend to wipe my externals clean as part of the conversion. It's my understanding that APFS is an optimization specifically designed to work with an ssd; will this cause any trouble with the spinners I have if I reformat them to APFS? (sorry if this is elementary but I simply don't know and don't want to run into any unforeseen issues) Thanks!!
  2. julianfairfax macrumors 65816


    Jun 11, 2018
    Switzerland - UTC+1 or UTC+2 during DST
    You cannot use APFS on Time Machine drives. Aside from those, APFS works on all drives with macOS 10.14 Mojave having introduced APFS for Fusion Drives and optimisation for Hard Drives.
  3. Porkchop Sandwich thread starter macrumors regular

    Feb 3, 2017
    Oh wow, glad I asked first. Thanks for letting me know that..I'll educate myself b/f proceeding any further b/c I already re-formatted one of the drives and now falling back to a legacy format doesn't seem to be an option. Thanks again.
  4. Fishrrman macrumors P6


    Feb 20, 2009
    My opinion only (take it for what you paid for it):

    DO NOT "upgrade" your external drives to APFS.
    Leave them at HFS+.

    They will continue to work fine.
  5. Porkchop Sandwich thread starter macrumors regular

    Feb 3, 2017
    Yes, that was a close one b/c I was set to leave myself w/out a drive for TM..not knowing what I didn't know nearly cost me.

    The drive I converted is pretty old but it never seems to miss a beat so storing family (archive) photo's and movie clips etc will be its intended use, along w/redundancy on another drive of course. SO glad I reached out to ask and thanks to the board for chiming in - saved me some bucks.
  6. haralds macrumors 6502a


    Jan 3, 2014
    Silicon Valley, CA
    Clearly see more spinning cursors on spinning disks with APFS, while there is little to gain in performance. My backup Mojave boot on my Mac Pro is on a spinning disk and it runs ok. But it feels slow.
  7. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    As noted, Time Machine does not support APFS. Per Wikipedia, Apple_File_System
    Since hard-linking is essential to the functioning of present-day Time Machine, Time Machine's replacement needs to be redesigned from the bottom up. I'm confident the designers of APFS have known this from the beginning and the necessary functionality has been provided for.

    While it's true that APFS is optimized for Flash storage/SSD (support for TRIM, for example), most of its benefits apply to spinning HDDs as well.

    Many capabilities of APFS seem perfect for Time Machine (snapshots, clones and deltas, whole-disk encryption, increased maximum number of files, crash protection, shared free space on a multi-volume disk...), with one very practical, beneficial result being that backups may require substantially less storage space. I also suspect the crash protection features of APFS (writing updated metadata to a new location, rather than overwriting/replacing the old metadata only after the new has been checksummed/verified) will improve the reliability of Time Machine drives stored on NAS.

    I expect that someday we will see a version of Time Machine that is specifically designed to use APFS. I suspect it will be given an all-new name, so it won't be confused with Time Machine. Even after the new Time Machine is released, HFS+ Time Machine will have to be supported for many years.

    Due to the use of hard linking, it's not enough to copy a Time Machine archive from an existing HFS+ drive to a new, APFS-formatted drive. The fundamental structure of the Time Machine archive has to be modified. This is likely to be a more complex and time-consuming process than the HFS+ to APFS conversion that takes place when you first upgrade a machine to High Sierra or Mojave. Long after New Time Machine is available, I suspect many people will decide to keep their existing Time Machine archives in HFS+, rather than go through conversion.

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6 October 28, 2018