There’s been some Friday night kernel drama on the Linux kernel mailing list… Linus Torvalds has expressed regrets for merging the Bcachefs file-system and an ensuing back-and-forth between the file-system maintainer.

    • DaPorkchop_@lemmy.ml
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      26 days ago

      ext4 is intended for a completely different use case, though? bcachefs is competing with btrfs and ZFS in big storage arrays spanning multiple drives, probably with SSD cache. ext4 is a nice filesystem for client devices, but doesn’t support some things which are kinda fundamental at larger scales like data checksumming, snapshots, or transparent compression.

        • DaPorkchop_@lemmy.ml
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          26 days ago

          XFS still isn’t a multi-device filesystem, though… of course you can run it on top of mdraid/LVM, but that still doesn’t come close to the flexibility of what these specialized filesystems can do. Being able to simply run btrfs device add /dev/sdx1 / and immediately having the new space available is far less hassle than adding a device to an md array, then resizing the partition and then resizing the filesystem (and removing a device is even worse). Snapshots are a similar deal - sure, LVM can let you snapshot your entire virtual block device, but your snapshots are block devices themselves which need to be explicitly mounted, while in btrfs/bcachefs a snapshot is just a directory, and can be isolated to a specific subvolume rather than the entire block device.

          Data checksums are also substantially less useful when the filesystem can’t address the underlying devices individually, because it makes repairing the data from a replica impossible. If you have a file on an md RAID1 device and one of the replicas has a bad block, you might be able to detect the bitrot by verifying the checksum, but you can’t actually fix it, because even though there is a second copy of the data on another drive, mdadm simply exposes a simple block device and doesn’t provide any way to read from “the other copy”. mdraid can recover from total drive failure, but not data corruption.

        • linearchaos@lemmy.world
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          26 days ago

          Like there’s not a bunch of stuff EXT 4 can’t do that BTRFS and whatever this other acronym soup can do.

          It’s the entire point of my post. E x t 4 does work but it doesn’t do the stuff these other file systems do so they are an advantageous choice for some things.

          • Riskable@programming.dev
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            26 days ago

            One point: ext4 has a maximum file size of 16TiB. To a regular user that is stupidly huge and of no concern but it’s exactly the type of thing you overlook if you “just use ext4” on anything and everything then end up with your database broken at work because of said bad advice.

            Use the filesystem that makes the most sense for your use case. Consider it every single time you format a disk. Don’t become complacent! Also fuck around with the new shit from time to time! I decided to format my Linux desktop partitions with btrfs over a decade ago and as a result I’m an excellent user of that filesystem but you know what? I’m thinking I’ll try bcachefs soon and fiddle around more with my zfs partition on my HTPC.

            BTW: If you’re thinking about trying out btrfs I would encourage you to learn about it’s non-trivial maintenance tasks. btrfs needs you to fuck with it from time to time or you’ll run out of disk space “for no reason”. You can schedule cron jobs to take care of everything (as I have done) but you still need to learn how it all works. It’s not a “set it and forget it” FS like ext4.

          • GolfNovemberUniform@lemmy.ml
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            26 days ago

            I think we’re just talking about different priorities. For me stability is the most important in production. For you features seem to matter more. For me it’s enough if a file system can store, write, read and not lose files. I guess it depends on what the use case and the budget are.

            • linearchaos@lemmy.world
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              26 days ago

              Yeah, some people have needs that you don’t have. That’s why I commented on your blanket statement of just use EXT4.

              I have BTRFS in production all over the place. Snapshots are extremely useful for what I do.

            • DaPorkchop_@lemmy.ml
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              26 days ago

              ext4 aims to not lose data under the assumption that the single underlying drive is reliable. btrfs/bcachefs/ZFS assume that one/many of the perhaps dozens of underlying drives could fail entirely or start returning garbage at any time, and try to ensure that the bad drive can be kicked out and replaced without losing any data or interrupting the system. They’re both aiming for stability, but stability requirements are much different at scale than a “dumb” filesystem can offer, because once you have enough drives one of them WILL fail and ext4 cannot save you in that situation.

              Complaining that datacenter-grade filesystems are unreliable when using them in your home computer is like removing all but one of the engines from a 747 and then complaining that it’s prone to crashing. Of course it is, because it was designed under the assumption that there would be redundancy.

      • Quazatron@lemmy.world
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        26 days ago

        No. You can layer ext4 with LVM and LUKS to get a lot of features (but not all) that you get with BTRFS or ZFS. FAT is not suitable for anything other than legacy stuff.

        • linearchaos@lemmy.world
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          26 days ago

          My point is there are features that you don’t get in EXT that are completely reasonable to use and workflows.

          When someone says just use EXT4, they’re just missing the fact that people may want or need those other features.

          Your response to FAT is exactly my point.

    • ByteJunk@lemmy.world
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      26 days ago

      Torvalds rejected the merge, and that’s pretty much what he said - no one is using bcachefs.

      There’s no reason for a “fix” to be 1k+ lines, these sorts of changes need to come earlier in the release cycle.

      • Riskable@programming.dev
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        26 days ago

        You had corruption with btrfs? Was this with a spinning disk or an SSD?

        I’ve been using btrfs for over a decade on several filesystems/machines and I’ve had my share of problems (mostly due to ignorance) but I’ve never encountered corruption. Mostly I just run out of disk space because I forgot to balance or the disk itself had an issue and I lost whatever it was that was stored in those blocks.

        I’ve had to repair a btrfs partition before due to who-knows-what back when it was new but it’s been over a decade since I’ve had an issue like that. I remember btrfs check --repair being totally useless back then haha. My memory on that event is fuzzy but I think I fixed whatever it was bitching about by remounting the filesystem with an extra option that forced it to recreate a cache of some sort. It ran for many years after that until the disk spun itself into oblivion.