APFS Bug in macOS High Sierra Can Cause Data Loss When Writing to Disk Images

Discussion in 'MacRumors.com News Discussion' started by MacRumors, Feb 19, 2018.

  1. MacRumors macrumors bot

    MacRumors

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    Apple's APFS file system included in macOS High Sierra suffers from a disk image vulnerability that in certain circumstances can lead to data loss, according to the creator of Carbon Copy Cloner.

    In a blog post last Thursday, software developer Mike Bombich explained that he had uncovered the data writing flaw in the Apple File System, or APFS, through his regular work with "sparse" disk images.

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    For those who aren't familiar with the term, a sparse disk image is basically a file that macOS mounts on the desktop and treats as if it was a physically attached drive with a classic disk volume structure. The flexibility of sparse disk images means they are commonly used in the course of performing backup and disk cloning operations, hence Bombich's extensive experience with them.
    Two related problems are identified by Bombich, above. The first is that the free space on the APFS-formatted sparse disk image doesn't update as it should when the free space on the underlying physical host disk is reduced. The second problem is the lack of error reports when write requests fail to dynamically grow the disk image, resulting in data being "written" into a void. Bombich tracks both bugs back to macOS's background "diskimages-helper" application service, which he has since reported to Apple.

    Bombich's video demonstrating the APFS bug

    Every installation of High Sierra on Macs with all-flash storage converts the existing file system to APFS, which is optimized for modern storage systems like solid-state drives. However, as Bombich notes, ordinary APFS volumes like SSD startup disks are not affected by the problem described above, so the vast majority of users won't be affected by it - the flaw is most applicable when making backups to network volumes. Bombich says Carbon Copy Cloner will not support AFPS-formatted sparse disk images until Apple resolves the issue.

    The APFS flaw follows the discovery of another bug in Apple's operating systems that received extensive coverage last week. That bug is induced by sending a specific character in the Indian language Telugu, which causes certain apps on iPhones, iPads, and Macs to freeze up and become unresponsive. The Telugu character bug has already been fixed in Apple's upcoming iOS 11.3 and macOS 10.13.4 software updates.

    Article Link: APFS Bug in macOS High Sierra Can Cause Data Loss When Writing to Disk Images
     
  2. kahkityoong macrumors 6502

    kahkityoong

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    #2
    Glad I reverted to Sierra when I deemed High Sierra a S-show after a couple of weeks. There seems to be no end to Apple's incompetence with this OS.
     
  3. amaze1499 macrumors regular

    amaze1499

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    quote: The bug has already been fixed in Apple's upcoming iOS 11.3 and macOS 10.13.4 software updates.
     
  4. BaltimoreMediaBlog macrumors 6502a

    BaltimoreMediaBlog

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    #4
    Wow, this makes me wonder. Did Apple and APFS destroy my only 2 year old Seagate drive with mostly disk images on it?

    I kept wondering, how could my newest standard HD used the least of all fail quicker then the much older ones? The complete failure boggles my mind. Seagate blamed harsh usage, but it was not the system drive, only contained media and music and disk images for specific purposes.
     
  5. navaira macrumors 68040

    navaira

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    #5
    But... Bugs in Apple software never happen! It's probably about Android!
     
  6. quaresma macrumors member

    quaresma

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  7. CmdrLaForge macrumors 601

    CmdrLaForge

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    Not cool. Data loss is a very serious bug. I hope Apple releases the fix soon.
     
  8. klunernet macrumors newbie

    klunernet

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    #8
    I wonder if this is related to high sierra suddenly invalidating my time machine backups to my NAS, and demanding to do a new full. (Loosing two years worth of history). Then doing it again 2 weeks later.
     
  9. JessePinkman, Feb 19, 2018
    Last edited: Feb 19, 2018

    JessePinkman Suspended

    JessePinkman

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    this happens randomly with steam games on my macbook pro it happened with pillars of eternity was almost crashing my nvidia gpu then i verified game files via steam client and it found few mb corrupted data for no reason (no power loss or resets) shh macos bugs these days...
     
  10. Novus John macrumors member

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    High Sierra has been a complete disaster for me. My computer locks up for 5-10 seconds every few hours. Probably some memory leaks or something. Either way this is really pathetic, even windows works better than this.
     
  11. Royksöpp macrumors 6502a

    Royksöpp

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    Another day, another bug. How very Apple-esque. #ifstevejobswasalive #firetimcook
     
  12. dannys1 macrumors 68020

    dannys1

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    Almost certainly not, your NAS won't be formatted as APFS.
     
  13. Loge macrumors 68030

    Loge

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  14. Royksöpp macrumors 6502a

    Royksöpp

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    Apple makes no mistakes. I love the notch, I embrace the notch. I think therefore I am, the notch.
     
  15. meaning-matters macrumors 6502

    meaning-matters

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  16. Lesser Evets macrumors 68040

    Lesser Evets

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    “Bombich”... you can’t make this stuff up.
     
  17. fermat-au macrumors 6502

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    It is bugs such as this, that this what for mission critical task sys admins don't update there system to the newest version for software the day or even week or month it ships.
     
  18. Kabeyun macrumors 65816

    Kabeyun

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    #18
    I feel your pain. Had a major memory leak after moving to Sierra, let alone High Sierra. Progressively unresponsive about 10 minutes after reboot. Wasn’t the notorious iTunes leak either. Couldn’t trace it. Went back to El Cap and am quite happy. My only complaint is that Photos can’t pick a new key frame from a live photo. I’ll live.
     
  19. BaggieBoy macrumors 6502

    BaggieBoy

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    Same happened to me, 2 new full backups required so far.
     
  20. Merode macrumors 6502

    Merode

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    #20
    Making fun of surnames. Feels like primary school already.
     
  21. tkermit macrumors 68040

    tkermit

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    #21
    No. Time Machine doesn't support backing up to APFS-formatted disk images, so this bug should have no effect on it.
     
  22. Eagle_Eye macrumors newbie

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    #22
    Anyone else noticed strange behaviour when creating a zip archive? There was a moment (when I was running High Sierra, downgraded to Sierra) where I had to re-zip a folder 6 times before APFS gave me the correct files. In all 5 previous versions the zip contained an older version of a Word file.
     
  23. dannys1 macrumors 68020

    dannys1

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    #23
    Same, Mike is a really good guy and we use CCC every day in work and it's my businesses number 1 tool for deployment, I prefer it over all other deployment tools that Mac Admins usually use.

    APFS has lot's of bugs - i've discovered two edge use cases. Rsync with Apples new AP controllers (which come in MacBook Pros built this year and iMac Pro's) runs 4x slower than normal (which makes a 10minute copy a 40 minute copy) - also APFS formatted raid drives when used as a boot volume take minutes to appear in the macOS boot menu.

    Both are edge cases that 99% of users will never experience (though the AP controller is a bigger deal and more and more people will come into that as those computers become more available, so it needs sorted with by Apple or the Samba team working on rsync...i've reported it to both)
    --- Post Merged, Feb 19, 2018 ---
    It's his surname?...
     
  24. JessePinkman Suspended

    JessePinkman

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    imo its hardware not software apple have been using cheap memories since tim cook
     
  25. Luigi55 macrumors newbie

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    #25
    Same problem happens on my MacBook Pro 13" Mid 2014.
     

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