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I'm glad Hammer FS exist, it is always great to have options, and new filesystems have more to build on. But this one seems weird to me: > copy-on-write, impl
by takeda 9y ago
I'm glad Hammer FS exist, it is always great to have options, and new filesystems have more to build on.
But this one seems weird to me:
> copy-on-write, implying snapshots and such, like ZFS, but snapshots are writable.
snapshot by definition should be read-only, also ZFS allows to create a new filesystem from snapshot (through zfs clone) which is also O(1) operation.
- antongribok 9y agoRead-only and read-write snapshots are possible with LVM, ZFS, Btrfs, and many commercial storage solutions. One reason why you would want a writable snapshot is during backup validation. An application may need to do crash recovery before being able to read data, and having a writable filesystem makes things a lot easier. I know that ZFS and LVM both send writes to a separate area, so the original snapshot is never modified (don't know about Btrfs implementation details).
- takeda 9y agoYes, what I said in ZFS you can instantly (and without using extra space) create a writable filesystem from snapshot using zfs clone (you can create multiple filesystems from one snapshot), but snapshots by itself are always read only.
- Someone 9y agoThat looks a bit like git versus svn. So, it _might_ be an insane idea that ends up being a good idea. Especially if the default is to have a read only snapshot, I do not rule that out.