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
    671·
    4 months ago

    bcachefs is way more flexible than btrfs on multi-device filesystems. You can group storage devices together based on performance/capacity/whatever else, and then do funky things like assigning a group of SSDs as a write-through/write-back cache for a bigger array of HDDs. You can also configure a ton of properties for individual files or directories, including the cache+main storage group, amount of data replicas, compression type, and quite a bit more.

    So you could have two files in the same folder, one of them stored compressed on an array of HDDs in RAID10 and the other one stored on a different array of HDDs uncompressed in RAID5 with a write-back SSD cache, and wouldn’t have to fiddle around with multiple filesystems and bind mounts - everything can be configured by simply setting xattr values. You could even have a third file which is striped across both groups of HDDs without having to partition them up.

    • NeoNachtwaechter@lemmy.world
      126·
      4 months ago

      two files in the same folder, one of them stored compressed on an array of HDDs in RAID10 and the other one stored on a different array […]

      Now that’s what I call serious over-engineering.

      Who in the world wants to use that?

      And does that developer maybe have some spare time? /s

      • apt_install_coffee@lemmy.ml
        35·
        4 months ago

        This is actually a feature that enterprise SAN solutions have had for a while, being able choose your level of redundancy & performance at a file level is extremely useful for minimising downtime and not replicating ephemeral data.

        Most filesystem features are not for the average user who has their data replicated in a cloud service; they’re for businesses where this flexibility saves a lot of money.

        • DaPorkchop_@lemmy.ml
          12·
          4 months ago

          It’s not that obscure - I had a use case a while back where I had multiple rocksdb instances running on the same machine and wanted each of them to store their WAL only on SSD storage with compression and have the main tables be stored uncompressed on an HDD array with write-through SSD cache (ideally using the same set of SSDs for cost). I eventually did it, but it required partitioning the SSDs in half, using one half for a bcache (not bcachefs) in front of the HDDs and then using the other half of the SSDs to create a compressed filesystem which I then created subdirectories on and bind mounted each into the corresponding rocksdb database.

          Yes, it works, but it’s also ugly as sin and the SSD allocation between the cache and the WAL storage is also fixed (I’d like to use as much space as possible for caching). This would be just a few simple commands using bcachefs, and would also be completely transparent once configured (no messing around with dozens of fstab entries or bind mounts).

        • pimeys@lemmy.nauk.io
          1·
          4 months ago

          I mean… If you have a ton of raw photos in one directory, you can enable the highest compression rate with zstd to it. Every other directory has lz4 with the fastest compression. Your pics take much less space, but the directory will be slower to read and write.