LWN: Comments on "XFS online filesystem scrubbing and repair"

maybe just maybe look at other systems ?

johnjones — Fri, 25 May 2018 12:02:04 +0000

seems strange that this is much of a debate

how does AIX/OS2 with JFS2 online scrub do it ?
how does Solaris/FreeBSD with ZFS do it ?
etc

Shades of mdraid ...

Wol — Thu, 24 May 2018 17:13:07 +0000

It seems most systems have difficulty passing an error back up the chain when there's a problem short of an out-and-out failure.

Raid, for example, could check majority voting if there's a mirror, or parity for raids 5 and 6. But at present, on a read, it just assumes everything is hunky-dory if the data blocks read okay. There is no mechanism for checking and indicating a problem. Okay, with a two-disk mirror or raid 5, there's nothing that can be done to fix an integrity error, but it would be nice to know it's happened. And if you know a disk is flaky it would be nice to be able to tell any fix utility to assume that's the problem. At present, the fix utilities assume by default it's the parity that's dud, so even with raid-6 an ill-informed "fix" will simply trash your data if that assumption isn't true.

Cheers,
Wol

XFS online filesystem scrubbing and repair

ju3Ceemi — Thu, 17 May 2018 15:15:26 +0000

A command which matches the "discard" feature (via fstrim) would be nice

XFS online filesystem scrubbing and repair

ehiggs — Thu, 17 May 2018 13:32:34 +0000

fsscrub, surely.

XFS online filesystem scrubbing and repair

unixbhaskar — Thu, 17 May 2018 04:20:33 +0000

Yup. fscrub.* would be a good piece to have. :)

XFS online filesystem scrubbing and repair

nix — Wed, 16 May 2018 21:58:46 +0000

Also, of course, scrubbing is *online*, unlike fsck. It's not really quite the same thing. (But dispatching from a fscrub utility to individual fscrub.* tools seems like a good idea to me too.)

XFS online filesystem scrubbing and repair

rahulsundaram — Wed, 16 May 2018 19:28:54 +0000

fsck is just a frontend. Each filesystem has it's own fsck utility

Examples:
fsck.cramfs fsck.ext3 fsck.fat fsck.msdos fsck.xfs
fsck.btrfs fsck.ext2 fsck.ext4 fsck.minix fsck.vfat

XFS online filesystem scrubbing and repair

pj — Wed, 16 May 2018 17:11:05 +0000

Shouldn't this functionality be rolled into fsck, and not another wrapper program? What am I missing?