Messages in this thread | | | From | Andreas Dilger <> | Subject | Re: [PATCH] SMP race in ext2 - metadata corruption. | Date | Sat, 5 May 2001 21:38:31 -0600 (MDT) |
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Chris Wedgewood writes: > As I said, I'm not takling about kernel based fsck, although for > _VERY_ large filesystems even with journalling I suspect it will be > required one day (so it can run in the background and do consistency > checking when the machine is idle).
Actually, I was talking with Ted about this, and we agreed that: a) kernel-based e2fsck is a pain in the a** (locking issues, etc) b) you can do an LVM snapshot of your live filesystem and do a read-only fsck on that to check if the filesystem is still OK. For journaled filesystems like reiserfs and ext3, they need to use the super method write_super_lockfs() to block I/O and flush everything to disk at the time of the snapshot, to ensure that they don't need recovery on a read-only device. This makes the LVM snapshot equivalent to unmount the filesystem, copy contents to a new device and remount the filesystem.
While (b) doesn't let you fix a filesystem online, unless there is a kernel bug or hardware problem, you should not have a problem. If you have either of those, then fixing the filesystem online is just asking for more problems in the future.
Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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