Re: Corrupted partitions

tytso@mit.edu
Tue, 29 Jun 1999 13:16:48 -0400


From: "Stephen C. Tweedie" <sct@redhat.com>
Date: Mon, 28 Jun 1999 18:36:28 +0100 (BST)

> Hang on! In an earlier email, you said that the reason that mke2fs
> preallocates 12 blocks to lost+found is because e2fsck has problems
> allocating blocks when fixing a corrupted file system, but now you
> state that no such problem exists !!! Which is it?

e2fsck has no problem in principle, but the disk may be full and there's
not much it can do in that case. Preallocating lost+found just
eliminates one extra possible error situation.

The other reason why you want to avoid allocating blocks via e2fsck
happens when part of the inode table has gotten munched, so that e2fsck
doesn't have an accurate listing of all the blocks which might be in
use. In such a case, an expert might very well want to link all
disconnected inodes into lost+found without allocating any blocks, and
then only later decide whether or not he/she needs to use a direct disk
block editor to try to recover really precious data that can't be saved
any other way.

But e2fsck can allocate blocks for lost+found (or the root directory for
that matter if it has been trashed). It's just that you want to avoid
doing if possible.

Of course, the right answer to all of this is to religiously back up all
of your data so you don't have to go to such extreme measures, but we
know how often people do backups, right? :-)

- Ted

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