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Re: LVM - dead disk

On Apr 1, 2006, at 21:14, Klaus Pieper wrote:

Which file systems are (or maybe were) on lvm? Do you need lvm to boot up the system? What about backups?

I do have some backups (amanda to dds3 dat) - so - it's not going to be a crisis if I can't get it fixed (although - getting the lastest copy of stuff would be good)

But - I thought this would be a good chance at trying to learn more about retrieving data when systems go bad. There is no large hurry to getting the box back up - so I'm willing to hack at it a bit - try to understand how to work with this kind of problem.

So - on to the system - /usr, /var, /home, /opt, /srv and /store were on lvm

/store is the dead disk - so that's out of the picture.

/opt, /srv, /usr - no useful info - /opt and /srv are just play areas - /usr is all reinstallable from the packages.

/etc is not on lvm - and is sitting there fine and pretty :)

So - I'm really after /home and /var/lib

All were backed up more or less often (there is a limit as to how much data a DDS3 can take). But - not being a prioritised box - it tends to be weekly rather than daily.

So - we've used the vgreduce command to remove the dead disk.

For some reason I can no longer log in. I may well have caused this myself - but it may be linked to the fact that this machine has nsswitch for login on ldap compat - and of course the ldap data is on /var/lib - however - the compat should let me in (I see root in the passwd and shadow files). And - it seems odd that it does not see a hostname.

So - I thought I'd try to chroot in from a CD live disk - knoppix was what I had lying around (4.0) - but that doesn't have lvm or has an lvm version difference.

Some time next week - I'll be sticking three new 250Gb disks into it and reinstalling from scratch - but - I'd like to attempt to get the data off if at all possible. Each time something goes wrong you learn a bit - you know ? :)

So - is there a live cd out there (or an install set or similar) that will boot far enough to allow me to chroot in and then load the virtual group? Or is there a better way?

In fact - I'm more after hints/tips on how to go about investigating/ troubleshooting this one than just getting the data back :)

And - with a bit of luck I'll manage to send this reply to the list directly first time this time :)

Chris Searle

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