(As I type this, the LVM on this workstation is busy merging back a snapshot take before a botched upgrade attempt from F17 to F18...)
ZFS's online scrub is sufficient because of it is atomic copy-on-write transaction commit, uberblock history and ditto blocks.Quote:
It is quite possible that Tux3 will get to incremental and online fsck before
Ext4 does. (There you go, Ted, that is a challenge.) There is no question that
this is something that every viable, modern filesystem must do, and no,
scrubbing does not cut the mustard. We need to be able to detect errors on the
filesystem, perhaps due to blocks going bad, or heaven forbid, bugs, then
report them to the user and *fix* them on command without taking the volume
offline. If that seems hard, it is. But it simply has to be done.
Granted, ZFS does have the upper hand here (and maybe, in the long run btrfs), but as it stands, LVM+ext4 is a *very* powerful (and proven) combination.