How long should it take to convert a normal HDD to APFS?

Discussion in 'macOS High Sierra (10.13)' started by trumpetmercenary, Jul 25, 2017.

  1. trumpetmercenary macrumors member


    Jul 24, 2017
    I started a conversion to APFS for my time machine backup, an external Seagate Backup Plus, about 45 minutes ago. It's still stuck on the last step, "reporting pre-conversion statistics."

    I know converting an SSD should only take a minute or two, but I wasn't sure about normal HD's. How long should I wait before giving up and assuming it failed?
  2. trumpetmercenary thread starter macrumors member


    Jul 24, 2017
    Well, it's been four hours now and still stuck at the same step, so I'm going to assume it hung. I read on another thread here that APFS doesn't support time machine, so maybe that's why. But a little odd that it would allow me to try to convert to APFS if they're not compatible.

    I'll leave it here overnight just in case, but I have the feeling I'm going to find a bricked time machine tomorrow morning!

    Build: public beta 2
  3. Erdbeertorte Suspended

    May 20, 2015
    Yes, TimeMachine is not supported on APFS drives yet. Also it is highly optimized for SSDs and I don't know if it does make sense on an HDD or could even harm it.

    If you install High Sierra on an HDD Mac the APFS option doesn't show up.

    Yesterday I converted the boot HDD to APFS on my Mid-2011 iMac from the recovery partition and now can't boot into macOS anymore. When I hold down option while booting only "Recover 10.13" is showing up.

    In the Recovery Disk Utility it looks like everything is still on the drive and a reinstall might fix it. But I don't now if this even works. Haven't tried it yet.

    But I tried a clean install of High Sierra from USB on my 12-inch MacBook with a pre-formatted APFS SSD and it did not work at all. I had to reformat it to HFS+ and let the installer do the conversion.
  4. trumpetmercenary thread starter macrumors member


    Jul 24, 2017
    Thanks for all of the info.

    Oddly enough, when I came back in the morning, it says the APFS conversion failed, but it still converted the disk to APFS anyway. See the errors...




    And yet, when I try to back up time machine...


    So I guess I really did brick my time machine! Really would have been nice if Apple warned me about this when I tried to press the convert button.

    Will Time Machine work with APFS in the future?
  5. oatman13 macrumors regular

    Feb 14, 2013
    Do not use APFS on standard rotational media. Also, time machine requires HFS+.
  6. HallStevenson macrumors 6502a


    May 1, 2012
    Nothing is "bricked". Try and copy some files to the external HDD and report back if it works.

    Your external HDD is just a hard drive in a box. Time Machine support isn't going to stop it from converting. Now, after it's converted, you won't be able to use it for TM storage but that's a different issue.
    It's perfectly okay to use it on regular, mechanical drives.
  7. trumpetmercenary thread starter macrumors member


    Jul 24, 2017
    Yeah, the drive itself still functions as a normal HD, but the time machine backup was completely broken. All of the folders and files in the backup are just aliases, and when you click on them it says that the original item can't be found. It's no big deal, since I can just wipe the drive as OS X Extended and start backing up to it again. I didn't lose anything.

    So, the takeaways from all of this:
    1) You can convert some normal HDD's to APFS, but it might take 20 hours, say it failed, and still work
    2) Don't ever convert a time machine backup you need to APFS because the two aren't compatible! Disk Utility won't warn you before you try to convert, though I still think it should.
  8. ignatius345 macrumors 68000

    Aug 20, 2015
    Crap. I wish I'd read this before I started this mess -- been going for 6 hours now, no end in sight.


    Aaaaand now I know that at the end of this I'm just gonna end up reformatting and doing a whole new Time Machine backup anyway. Lesson learned: don't leap into crap before checking around!
  9. ignatius345, Mar 21, 2018
    Last edited: Mar 21, 2018

    ignatius345 macrumors 68000

    Aug 20, 2015
    For anyone who makes the same mistake I did -- Disk Utility wasn't offering me the option to convert back to HFS+ so I could use the drive for Time Machine again, but I found these instructions, which worked for me. It's a destructive operation, of course, and your old data is toast.

    Important: there's a typo in the article, and where it says

    diskutil apps deleteContainer /dev/[your disk ID]
    that won't do anything because "apps" is invalid (which fortunately a commenter points out).
    Instead type "apfs", so:

    diskutil apfs deleteContainer /dev/[your disk ID]
    Note that [your disk ID] is of course not part of the code, but you'll find that out in the instructions.
  10. madrich, Mar 21, 2018
    Last edited: Mar 21, 2018

    madrich macrumors 6502


    Feb 19, 2012
    World Class City of Chicago
    Soooooo, if I understand this situation correctly, when you upgrade (instead of clean install) to High Sierra, HS will convert the existing data on my laptop to APFS,. However, the data files on the Time Machine backup will remain HFS+. RIGHT?
  11. ApfelKuchen macrumors 68030

    Aug 28, 2012
    Between the coasts
    You misunderstand a fundamental - your files do not get modified in any way. The file system that underlies those files is changed. To over-simplify, it's like moving the same files and folders to a new-style filing cabinet. The file system determines how files are manipulated and stored (exactly what happens when you read/write, copy, move, delete, etc.), but the files themselves continue to remain readable on any Apple-compatible file system (HFS+, FAT32, APFS). So, it doesn't matter that your internal HD is APFS but your Time Machine drive is HFS+.

    There's no difference between a clean install or an update install of High Sierra - if you have an SSD/Flash storage as your startup/system disk, it will convert that drive to APFS.
  12. ignatius345 macrumors 68000

    Aug 20, 2015
    As noted in the post above, you're basically right, but your files aren't getting modified, just the drive format is changing.

    Whatever you do, just don't get clever like I did and try to convert your Time Machine drive to APFS or you'll nuke your backups. (Five days later and my 5TB external drive is still in the process of reencrypting itself :/ )
  13. haxAT macrumors newbie


    Dec 19, 2018
    Took about 24 hours to convert a 3TB Fusion drive to convert to apfs. Looked like it stopped but continued working. So anybody who runs into this issue give it a LOT of time.

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