Disk filesystem developments

I was remarking to a colleague the other day that the reason there is so much filesystem development these days is that it is deeply understood, if not often expressed, that there are features which people want in a filesystem that are not available in any of the current filesystems. The problem, in my opinion, is that development efforts are so splintered that the lack of certain features does not lead to 1 or 2 new filesystems but far more. For disk file systems there is already Btrfs, NILFS, ext4, ChunkFS, Tux3, and more. And then there are cluster file systems…

For disk filesystems I think the 2 features most wanted are versioning / snapshots and data checksumming.

FS Development I’m watching

• ext4 - doesn’t offer much in the way of new features over other journaling filesystems but may have a future as an easy transition from systems running ext3.
• Btrfs - uses copy on write instead of journaling with support for extents, snapshots (including writable snapshots), checksums, and subvolumes. This is basically the closest thing Linux may get to the feature set of zfs.
• NILFS - is more developed than the other new filesystems and is actually usable. Offers a nice set of tools for snapshots though does not support checksumming. Also the snapshots are per-volume where other filesystems have either sub-volumes or snapshots at the directory or file level.