Eric,
There was a great article in the latest Linux Magazine (August 2000) about
Journaling Filesystems. It covers the current extfs2 filesystem and how it
works down to the inodes and what happens during a crash, i.e. how a crash
causes lost inodes to be placed in the lost+found directory. Here is a
quote from the article...
"...all of the entries in the corrupted directory can be "lost," (which
means they get linked into the lost + found directory for each filesystem.
Blocks put into the lost + found directory are in use, but there is no way
to know where they are referenced from)."
The article then goes into how a journaling file system works and
descriptions about each that are going to be available in the near future
such as XFS - from Silicon graphics, JFS - from IBM, Ext3fs from Stephen
Tweedie and Red Hat, and others. The article will be found at
www.linux-mag.com as a back issue in about 2 months as they won't put
current issues on the web.
Hope that helps.
Mark Holbert
mark@linuxsoftware.org
>Date: Fri, 4 Aug 2000 22:27:37 -0700 (MST)
>From: Eric Thelin <eric@thelin.org>
>To: plug-discuss@lists.PLUG.phoenix.az.us
>Subject: fsck fails/lost+found questions
>Reply-To: plug-discuss@lists.PLUG.phoenix.az.us
>
>I have a machine running a database that has crashed a number of times
>due to flaky power/UPS issues. I know this is VERY bad and have since
>fixed it. But that is not the point that I have a question about.
>Every time this machine crashed it would fail the fsck on startup to the
>point that I had to login and run fsck manually. When running manually
>I get asked a lot of questions about deleting duplicate inodes and
>inodes with bad times (or something like that it has been a long time).
>Because I didn't know what else to do I just went with the default which
>was always Y. After a while I went started adding a -y which just
>answers Y and doesn't even ask. So now the big question that I have is
>what dammage has been gettin done and is there anything that can done
>about it? Other than the obvious don't let the power fail or run a
>journaling filesystem. I now have thousands of entries in my lost+found
>directory that I assume came from these filesystem scans as some kind of
>safety net. But what could I do with them? If there is no way for a
>mere mortal to use them is it safe to delete them? They have seemingly
>random permissions, ownership, and timestamps so I am vary scared to do
>anything with them. My guess is that they are essentially hard links to
>the block that was dammaged. But I am certainly no fs hacker and I have
>never seen any documentation explaining lost+found or what to do with
>it. Any help would be great and probably enlightening to many people on
>this list.
>
>Eric Thelin
>aztechbiz.com
>
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