macOS 27 does not support CoreStorage volumes

(wadetregaskis.com)

138 points | by colejohnson66 a day ago ago

103 comments

  • Marsymars a day ago ago

    Well, heck.

    I posted ~7 months ago about my decision to use HFS+ for backups, and had a couple skeptical replies. (https://news.ycombinator.com/item?id=47317123)

    I guess I misjudged Apple's commitment to support HFS+ long-term.

    It now seems like there's no real native way of doing encrypted backups to HDDs on macOS (APFS not really recommended for HDDs)... the options are either encrypted Time Machine to a network location, or a third-party tool.

    Guess I'll figure out SuperDuper or Carbon Copy.

    • lakeviewterrace 21 hours ago ago

      > encrypted Time Machine to a network location

      this has a bonus feature where it will slowly corrupt itself over time and offer to start a completely new backup instead.

      • yangm97 19 hours ago ago

        That would happen around once a year when I used the 2013 AirPort Time Capsule.

        It seemed to stop killing itself when I moved to a ZFS backed samba share.

        Funnily enough I also kept snapshots enabled because I was expecting TM to bork itself eventually, so I could always rollback to a working state but I don’t remember needing to use that.

        • nijave 18 hours ago ago

          Eh, mine was always on zfs first on FreeNAS then Ubuntu and it didn't seem to help.

          The only thing that definitely made it worse was smb over openvpn. It'd corrupt itself every couple months instead of once or twice a year.

          • themanualstates 18 hours ago ago

            I also had a recurring corruption issue using a Windows Server file share.

            Before MacOS 27, I was always able to remove the Time Machine destination, replace the corrupted sparse bundle with a fresh empty one, and reconfigure that as the new TM destination. I even made a script for this, so I didn’t have to figure out the terminal commands every time.

            Unfortunately the script doesn’t work anymore; it throws ‘error 25’ on my MacOS 27.

            What’s weirdest is that, before the corruption, TM backup and restore used to work fine on my MacOS 27. Seemingly the backup functionality works as normal, but setting the TM destination was broken.

      • js2 19 hours ago ago

        I backup to TrueNAS which configures Samba/ZFS to take a snapshot before each backup. If TM decides to corrupt a backup, I can revert to a snapshot. I've only ever had to do this once in years of operation with several Macs backing up (each to their own share).

      • thfuran 20 hours ago ago

        Sometimes it's pretty quick.

      • mistrial9 18 hours ago ago

        to go forward, you must backup

    • AceJohnny2 21 hours ago ago

      > I guess I misjudged Apple's commitment to support HFS+ long-term.

      One thing I have learned with (current) Apple is to never trust their commitment to support something they're not using. And even be wary for stuff they are using. (in my mind, a core technical difference between Microsoft & Apple is that MS will bend over backwards for backwards compatibility, whereas Apple will drop it as soon as they can, and sometimes sooner still)

      They replaced their use of HFS+ with APFS in 2017, so it's had a good run.

      • AceJohnny2 21 hours ago ago

        I have heard from ex-CoreOS (the Apple org) colleagues is that the organization is run intentionally lean, because the leadership believes that people do their best work under pressure. This leads, among other things, to aggressive YAGNI pruning.

        • jiveturkey 14 hours ago ago

          sorry for the non-substantive nit. because we all know what you meant.

          YAGNI is about not doing work in advance. it's very confusing to say YAGNI and pruning in the same breath. it's also confusing to call this aggressive since it's been 10 years.

          i wouldn't call it dead code pruning either, since the code in question here was actually reachable and used. maybe, unmaintained code pruning?

          • natch 9 hours ago ago

            Pruning of proposed features maybe?

      • unsloppable 19 hours ago ago

        Rosetta..

        • tonyedgecombe 10 hours ago ago

          Is dead in next year's release (apart from a handful of exceptions).

    • mrpippy a day ago ago

      I don't think APFS was designed or tuned with HDDs in mind, but it will work just fine. Especially for backups where random read/write performance is not important.

      • MilaM a day ago ago

        I would not recommend using an APFS formatted HDD for Time Machine. It's painfully slow. With my Samsung T7 the hourly Time Machine backups are usually finished after a couple of minutes. Using my older HDD they can easily take 20 minutes to half an hour.

        • outofpaper a day ago ago

          While time machine used to be snappy on HDD it was build out of one of the weirdest little hacks hard links in folders. The new Time Machine might front a similar front end but under the hood its a different beast. You're having to mount snapshots as you move through time.

        • fl0id a day ago ago

          are you sure that is because of apfs? hdds are usually much slower, no?

          • zimpenfish 21 hours ago ago

            It's definitely APFS. I've had the pleasure* of HFS+ and APFS on the same external HDD and APFS is horrible. Given it is optimised for solid-state drives[0], it's understandable there'd be some slack but it is absolute horse paste.

            (If I could create an encrypted external HFS+ volume, I would but macOS hasn't allowed that for a while as far as my experience goes - it's non-encrypted HFS+ or encrypted APFS.)

            [0] https://support.apple.com/en-gb/guide/security/seca6147599e/...

          • MilaM 13 hours ago ago

            My point is that while the old HFS+ based Time Machine was performing ok on spinning disks, the new APFS based TM backups are excruciatingly slow and take ages to finish. I did actually compare both types on the same hard drive and even then the difference was very obvious.

    • 1over137 16 hours ago ago

      >It now seems like there's no real native way of doing encrypted backups to HDDs on macOS

      Be happy they let you backup to HDDs at all. :) They don't sell HDDs, so I'm half amazed they still work whatsoever.

    • hoherd 19 hours ago ago

      This might be a blessing in disguise for you. The silent data rot of HFS+ is what pushed me to ZFS. I would never go back to HFS+.

    • stingraycharles 21 hours ago ago

      Ok I may be an idiot, but I just have a permanently attached external disk that does Time Machine, what am I missing out on? Why network location? Or are you backing up massive amounts of data? (for me it’s just 2TB)

      • tonyedgecombe 9 hours ago ago

        This is what I do. It's the happy path and works well.

        It seems most of the problems with Time Machine happen when you try and run it over SMB. It's not that surprising when you realise what it is doing under that scenario. It creates a virtual disk on the remote and then formats it with APFS. You don't need much to go wrong to corrupt the backup in this scenario.

      • Marsymars 21 hours ago ago

        Oh right — I could do a local HFS+ non-encrypted disk with encrypted Time Machine (I assume) — that just slipped my mind.

      • mahboi 19 hours ago ago

        It's mainly for multiple people in a household to back up to one location, especially if some have laptops that are often not on desks. Those Airport APs used to also let you attach disks for this. You could even do it over a VPN.

        • stingraycharles 19 hours ago ago

          I so miss these Airport APs, I really don’t understand why the product line was cancelled, it was perfect.

          • mahboi 18 hours ago ago

            Same, I still have one for random purposes. Still the easiest and most polished router/AP, has lots of features.

      • root9876 20 hours ago ago

        I switched to Borg on Linux server from local attached Time Machine disk after once I went to a long trip and forgot the disk at home.

    • pinyen_cheng 12 hours ago ago

      Yep, never trust Apple for something they don't rely on to live. For example, don't expect the ecosystem with the Homepod with screen can last for too long. The support will drop and only leave security response if nobody is purchasing.

    • mahboi 19 hours ago ago

      Wait, you can do encrypted backup to a network location but not to HFS+? What if the network location is just your own Mac?

    • mahboi 15 hours ago ago

      Well I'm in your boat. Encrypted sparse bundle disk image on an HFS+ volume seems like it should work, if I'm not missing something. You only need CoreStorage for encrypted HFS+.

    • isityettime a day ago ago

      Can you use OpenZFS?

      https://www.openzfsonosx.org/

      • mahboi 15 hours ago ago

        I had to cmd+f "FUSE" all over the place first, thank goodness 0 matches

        • isityettime 6 hours ago ago

          They are working on a userspace port, since newer versions of macOS don't/won't allow third-party kernel code ("kexts"). But it's based on Apple's newer FSKit API directly, not macFUSE or FUSE-T.

          • mahboi 3 hours ago ago

            I just remember Google macfuse, osxfuse, then the new non-Google macfuse never working right for one reason or another. Don't think it was even a kernel vs userspace issue, it's just that the project kept changing ownership and getting broken by OS updates for other reasons, and it was confusing to find help because of the naming.

      • Marsymars 16 hours ago ago

        I could, but I don't want to make my wife figure that out if I get hit by a bus.

      • Joel_Mckay 19 hours ago ago

        MacOS is only Posix like, and does a lot of weird nonstandard things in the background regarding mounting drives/images.

        There are restrictions on where things can run, what can run, and what is accessible to the process.

        SSHFS is slow, but at least can mount windows/linux/android systems over VPN without issues. Look at what is needed to bring up SSHFS or NTFS support, and you should have a better idea of Apples walled garden policies.

        Apple makes information appliances, and not general-purpose computers. Some may disagree, but they usually choose an exception use-case rather than the normal experience of users. =3

        https://rclone.org/install/

    • qmr 19 hours ago ago

      ZFS

  • someonehere 21 hours ago ago

    With macOS 27, I don't know who Apple is trying to outdo?. 27 has been a total disaster for me and my setup at home.

    Back when there was a little more rivalry between Microsoft and Apple, Apple would come up with these really cool things to showcase the operating system and make lives easier. Now, I don't know what it is they're trying to prove with this operating system. I also hate the fact that they skinned the whole operating system around a failed hardware product.

    • tonyedgecombe 9 hours ago ago

      I always wait until the new year before I upgrade, I guess this is why I don't seem to have any major problems with it.

    • zombot 9 hours ago ago

      I think they're trying to be even shittier than Microslop.

  • AceJohnny2 21 hours ago ago

    FWIW, this is listed as deprecated in the Release Notes:

    https://developer.apple.com/documentation/macos-release-note... (Search for CoreStorage; their fragment links are hilariously broken)

    The premier 3rd Party technical blog Eclectic Light talked about it in June: https://eclecticlight.co/2026/06/17/what-to-do-with-your-enc...

    I can't immediately find prior warnings that this was coming.

    The following technical note from July 22nd says Encrypted HFS+ Volumes won't be supported in macOS *28*, so this seems a bit early... https://support.apple.com/en-us/125615

  • hmartin a day ago ago

    Also dropped support for FireWire drives, as I just found out the hard way.

    • traceroute66 a day ago ago

      > Also dropped support for FireWire drives, as I just found out the hard way.

      Erm... it was dropped in macOS 26 back in 2025 ?

      https://www.techspot.com/news/108394-usb-killer-dead-apple-d...

      • duskwuff a day ago ago

        And even that was 13 or 14 years after Apple shipped their last computer with a Firewire port - long enough that those computers weren't even supported by macOS 26. Apple dropping support for a largely obsolete technology, which they hadn't used for well over a decade, should hardly come as a great shock.

        • hmartin 17 hours ago ago

          It is actually shocking to no longer be able to access my data with literally no warning.

          As in, not even a dialog saying "hey this drive isn't support anymore"... just... nothing.

          What exactly is Apple gaining by dropping a (presumably) super stable driver??

          Nice that you can dismiss this as "largely obsolete technology" tho.

          • mahboi 14 hours ago ago

            I'd be annoyed. This stuff is usually not a big deal by itself but becomes death by a thousand cuts. Every OS update breaks something.

        • jasomill 20 hours ago ago

          Apple's Thunderbolt FireWire 800 adapter daisy-chained with their TB2-to-TB3 adapter should work on any modern system with Thunderbolt and FireWire support, as it just presents as a bog-standard PCI FireWire card.

          So worst-case, you should be able to access your old drives on a modern Mac by booting from a FireWire-compatible OS (Asahi or older macOS) on an external drive.

        • conradev 20 hours ago ago

          You used to be able to chain three adapters:

          Thunderbolt 3 to Thunderbolt 2 Thunderbolt 2 to FireWire 800 FireWire 800 to FireWire 400

          to plug a modern Mac into an iMac G4 in Target Disk Mode

          Now you need to add another layer: virtualizing old macOS on a modern Mac

          • mahboi 19 hours ago ago

            But you can still use the original 2005 iMac G5 remote with a new Apple TV

            • duskwuff 14 hours ago ago

              Is it specifically supported, or does it only "work" inasmuch as the Apple TV can be programmed to respond to most IR remotes?

              • mahboi 5 hours ago ago

                It works out of the box, you don't need to make the Apple TV learn it

        • RulerOf 21 hours ago ago

          I had one plugged into the FW800 port of my Cinema Display.

          Only really used it as a scratch drive for junk but it was still handy.

      • hmartin 19 hours ago ago

        Yes, thanks for the correction. I skipped 26 but could no longer hold out :)

      • conradfr 20 hours ago ago

        Ah yes 2025, the ancient times.

    • phony-account 11 hours ago ago

      People are mentioning Firewire hard-drives in this discussion, but much more significant are the industries where other Firewire devices are still in use: such as high-end film-scanning, music production, video archiving, and medical imaging.

      Notice that the common thread here is that Firewire was (and is) predominantly a tool for active CREATIVE functionality. Whereas Apple's current focus is passive CONSUMPTION functionality.

    • flanz_10 a day ago ago

      did you go from 25 to 27?

    • reaperducer a day ago ago

      Also dropped support for FireWire drives, as I just found out the hard way.

      Well, I guess I can finally throw out all those FireWire cables I have "just in case."

      Fortunately, my FireWire drives also support other interfaces, though far more slowly.

      • lproven 12 hours ago ago

        Stick them on eBay or at least Freecycle. They are getting hard to find now.

        For 2 elderly HP Microservers I need eSATA caddies, and those I cannot find at all anywhere.

        • washadjeffmad 3 hours ago ago

          Ah. Mine died a few years ago and I just got rid of them, or else I'd have shared.

      • mahboi 14 hours ago ago

        It's kinda wild how long external HDDs, not even SSDs, were bottlenecking themselves on USB 2. I don't get why they didn't just use eSATA.

  • exabrial a day ago ago

    MacOs 27 is a disaster. All of the sudden, I have 35% of a computer left to do any kind of work.

    • thisislife2 a day ago ago

      It's the iOSsification of macOS. Apparently, newer macBooks will now have touchscreen too ... once iPad OS and macOS are fully merged into OneMacOStoRuleThemAll, they'll finally lock down the bootloader on all Macs (why do you want to install anything else other an Apple OS?) and force all software install only through the App Store.

      • tonyedgecombe 9 hours ago ago

        People have been complaining about this for years and it hasn't happened.

        • bel8 5 hours ago ago

          In part it already did.

          Large margins, large round corners, now touchscreen.

          • tonyedgecombe 4 hours ago ago

            That’s a long way from locking down the bootloader the go was talking about.

        • bigyabai 2 hours ago ago

          Can you imagine if people said this about political catastrophe?

          "Yes, war with Iran has been threatened many times but we can rest assured it will never happen because nobody has done it before."

    • R1D3R a day ago ago

      Apple software updates are always a downgrade. It's an opportunity to abuse customers that Apple just can't resist. If you're lucky all they do is break your muscle memory by moving buttons pointlessly.

      • thewileyone 19 hours ago ago

        Gave up on Apple after my MBP is effectively stuck in High Sierra and can't run anything modern, no thanks to the App Store removing older versions of software.

        • lproven 12 hours ago ago

          OCLP is a lifeline and works well. After I finally bit the bullet, my iMac is faster than it was before.

    • drooopy a day ago ago

      Among other signs of awfulness, macOS 27 (and 26 before it) half the battery life of my M1 Air, forcing me to stay on Sequoia for a 2nd year.

    • icedchai a day ago ago

      26 felt like more of a disaster than 27! I waited about 8 months to upgrade to 26, and upgraded to 27 right away.

    • otterley a day ago ago

      What does that mean?

      • sys_64738 a day ago ago

        Maybe referring to the Apple Superintelligence being auto-added to macOS 27.

        • varispeed a day ago ago

          I'll wait for Apple Supremeintelligence in macOS 29

  • p0w3n3d 14 hours ago ago

    tar|crypt then

  • varispeed a day ago ago

    I upgraded and this system is a dumpster fire. Lags, random crashes, performance issues, random CPU spikes...

  • throwaway27448 a day ago ago

    For those of you who have never heard of this, it's macos's LVM. Why they didn't just refer to it as LVM is beyond me.

    • duskwuff a day ago ago

      > Why they didn't just refer to it as LVM is beyond me.

      Because it isn't LVM, and giving it the same name as another similar-but-distinct technology would just make matters more confusing.

      • Grombobulous a day ago ago

        According to the Wikipedia article about CoreStorage, it seems like the primary/only use case was Fusion drives (hybrid SSD/HDD hardware).

        The article says “It renders your expensive storage hardware completely useless.” but I’m really curious what that hardware could actually be. This seems like a pretty dead technology.

        • MilaM a day ago ago

          CoreStorage was also used for HFS+ formatted and encrypted external storage like Time Machine backups. If you have any of those in your archive you might not be able to read them in the future.

        • kstrauser a day ago ago

          I've gotta agree. I'm not sure what expensive storage hardware would be both relevant today and unable to migrate off CoreStorage. For example, my most expensive storage is a NAS with an iSCSI target, and it couldn't care less what blocks I write to it. If I had a CoreStorage setup on it, I could migrate the data to a new target and then reuse that space for something else. The hardware wouldn't mind, or even know, that I'd changed what's on it.

          You mentioned old, obsolete Fusion drives. I'm having a hard time thinking of anything else where that'd matter, so you're probably right about that. AFAIK you can reformat those to use something other than CoreStorage if you're actually stuck using those boat anchors.

        • mikepurvis a day ago ago

          Sidebar, but as an end user, I remain annoyed that there isn't seemingly something that's a worthy successor to fusion drives.

          Like I have an Unraid box with dual NVMe (RAID1) as the "cache" drive and a bunch of spinning disks as the "array", but it's also very manual, like torrents get downloaded first to cache and then a nightly job syncs them to the array. Feels like a real missed opportunity to not be able to have this kind of config transparently managed.

          • Grombobulous a day ago ago

            The successor is SSDs, and I think for what Apple was using fusion drives for they are worthy successors.

            The 2.5” form factor also took up a ton of space in a laptop form factor.

            With my NAS box (TrueNAS ZFS) I don’t bother with a cache. I struggle to justify the cost/benefit ratio. The sustained write speed of a 3.5” disk isn’t so bad for the most common NAS use cases.

            If I could go back to 2024 I think I’d use a m.2 2280 array for my NAS just because my present tense brain would think it was cheap. I don’t even hoard that much content so 4-8TB would be fine.

            Maybe one of these nifty things would be fun: https://www.bee-link.com/products/beelink-me-mini-n150

            • mikepurvis 15 hours ago ago

              From a pure cost point of view, I think it still makes sense to me to split the load, like 500GB of NVMe covers your containers and apps and stuff, but then 10-20TB of spinning storage is fairly achievable with redundancy, whereas that would cost a fortune to do as all solid state.

              The case I have is a Jonsbo N2, which works great for accommodating 5 3.5" drives with backplane, a mini-ITX mobo: https://www.amazon.ca/N2-Aluminum-Support-Integrated-Removab...

          • hypercube33 21 hours ago ago

            Windows storage spaces can do this as well. It's been pulled from the non server line for 11 years or something.

          • jmgao a day ago ago

            bcachefs with foreground_target/background_target/promote_target set appropriately does this automagically: https://bcachefs.org/Caching/

            • mikepurvis 15 hours ago ago

              Ah nice, I appreciate the search term, and I see there are some projects out there leveraging this, for example: https://github.com/nasty-project/nasty

              Overall I'm happy enough with Unraid for the moment, but I will definitely check in on bcachefs-based solutions when I'm next considering a rebuild/upgrade.

        • hagbard_c a day ago ago

          I have one of those in an ageing late 2009 27" iMac running Linux. It is a Seagate ST2000DX001-1CM1, a 2TB "SSHD" which comes down to having 8 GB of NAND storage bolted on to a conventional 2TB drive. It doesn't need any special driver to do its thing so I wonder what that CoreStorage bit is supposed to be about.

          • wtallis a day ago ago

            Did you install that SSHD as an aftermarket upgrade? I thought the Fusion Drive configurations shipped by Apple used normal hard drives and separate SSDs and were purely software-managed (and also used much more than 8GB of flash).

          • mrpippy a day ago ago

            Apple sold iMacs for many years that had a completely separate SSD and HDD, and CoreStorage was used to combine them into a single block device which was then partitioned and formatted as HFS+ or APFS.

            • mahboi 14 hours ago ago

              You could also do this to your own SSD and HDD, though probably only a good idea with internal ones like in a Mac Pro

      • throwaway27448 a day ago ago

        Does it not manage logical volumes?

        • wolvoleo 17 hours ago ago

          Yes it does. It's basically lvm for Mac. I wonder what they do now. Do they go back to old style fixed volumes?

      • sysguest a day ago ago

        ...like route 53? which is "dns configuration, but fancier"

        • zamadatix a day ago ago

          AFAIK "Route 53" was a net new name for such a product?

    • vondur a day ago ago

      It doesn't really do everything that a real LVM does though. This was used to support those annoyingly bad Fusion Drives. They dropped them around 2020 I think.

      • throwaway27448 a day ago ago

        > It doesn't really do everything that a real LVM does though.

        It manages logical volumes. Any quibbling is a matter of degree.

  • whatever1 a day ago ago

    Why do people try to force macOS things that it does not like to do? macOS does not like not apple hardware, period.

    For backups use a NAS. You can find from completely plug and play options to bring your own machine ones.

    • mahboi 19 hours ago ago

      "Not Apple hardware" meaning an external disk? It's not like the NAS is Apple either. They don't sell NAS or external disks anymore.