Other error rates that need to be looked at. [LWN.net]

Other error rates that need to be looked at.

Posted Jul 8, 2006 17:51 UTC (Sat) by giraffedata (subscriber, #1954)
In reply to: Other error rates that need to be looked at. by valhenson
Parent article: The 2006 Linux Filesystems Workshop (Part III)

Several times in the article and comments, I've seen the implication that FSCK corrects errors -- at least metadata errors -- in a filesystem. But FSCK as I understand it hardly does that at all. It corrects inconsistencies, and sometimes it corrects an inconsistency by replacing a lost and redundant piece of metadata.

But there isn't that much redundancy in e.g. ext2, is there? If a disk error or system crash causes a filesystem to lose a file's inode, FSCK "corrects" that error by deleting all the file's blocks too, right?

As a consistency restorer, there's nothing FSCK can do with file data -- from the filesystem perspective, the data is always consistent no matter how much it gets corrupted.

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Other error rates that need to be looked at.

Posted Sep 5, 2006 21:48 UTC (Tue) by anton (guest, #25547) [Link]

from the filesystem perspective, the data is always consistent no matter how much it gets corrupted.

Yes, many file system designers only care about metadata consistency. Note how doublefs is suggested as a replacement for copy-on-write filesystems, even though doublefs only duplicates the metadata; with update-in-place for data, I don't really see an efficient way to guarantee that the data is consistent.