Paul P Komkoff Jr wrote:
Replying to David Woodhouse:
RAID is just a hack which hides the redundancy from the file system; the kind of thing we always used to have to do for DOS compatibility so that we could provide an INT 13h handler and have it 'just work'. It's much the same reasoning which led to the built-in 'translation layers' on cheap CF cards and USB sticks which so often eat your data and which have a tendency to use up their limited lifetime in copying obsolete sectors belonging to deleted files around on the underlying medium.
We don't _need_ that kind of layering in Linux. Have a library of functions which can be used for such redundancy, by all means -- but don't just make RAID pretend to be a 'standard' block device and prevent all possibility of sharing knowledge between the file system and the layer providing the redundancy. That's just insane.
Well, everything you said habove is correct. But I've yet seen any "redundant block device filesystem" project anywhere.
Sun zfs, Isilon OneFS, possibly others.