Repairing a defective UFS 2 partition with another BSD's fsck

Polytropon freebsd at edvax.de
Wed Mar 25 14:48:16 PDT 2009


Dear -fs list,

last night I had an idea how I could have a chance to repair my
defective UFS partition. To remember, this is the whole story:
http://kerneltrap.org/mailarchive/freebsd-fs/2008/11/2/3894714
"Repairing a defective UFS 2 partition with fsck_ffs (or other means)"

I thought about the following:

As far as I know, UFS isn't only used by FreeBSD, but also by
OpenBSD and NetBSD. Variations should be less than, let's say,
with Solaris UFS. So it may be that I can use the fsck utility
of OpenBSD or NetBSD to check and repair the UFS dd duplicate
where FreeBSD's fsck fails with

	fsck_ffs: bad inode number 306176 to nextinode

To use with NetBSD, I've got a NetBSD Live! 2007 live system
CD here. For OpenBSD... well, I don't know if they offer any
live file system?

The only commands I'd need are mount and fsck (both for UFS
only). The system should be bootable via CD. Then I would need
a shell to do something like this:

	# mkdir /temp
	# mount -t ufs -o rw /dev/wd1s1c /temp
	# cd /temp/rescue
	# fsck -t ufs -yf ad1s1f.dd

In case NetBSD's or OpenBSD's fsck can't operate on the bare file,
I'd think about something like:

	# mkdir /temp
	# mount -t ufs -o rw /dev/wd1s1c /temp
	# cd /temp/rescue
	# mdconfig -a -t vnode -u 10 -f ad1s1f.dd
	# fsck -t ufs -yf /dev/md10

What do you think, is this even possible? Should I try it?




Please keep me CC because I'm on the questions@ list only. Thanks!

I'll cross-post it to questions@ in case someone there as an idea
for this really strange problem - remember, I'm the second (!)
being on this planet having encountered this particular problem.

I hope that's an acceptable behaviour. :-)



-- 
Polytropon
>From Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...


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