LVM problems

I've just rebooted my server after approx 3 months uptime and upon reboot my vgscan tells me it can't find one of devices that made up the volume group. There doesn't seem to be anything wrong with drive but none of the lvm tools will recognise it. The drive was added recently and the group extended across to it. Any chance of recovering the data on the drive that's still intact?

Bugger, it looks like I can only restore the partitions that were on the good disk. As soon as they were extended onto the dead drive the whole partition was lost.

EDIT: So that means my /tmp directory is intact but I've lost /home and all my myth recordings. If it's not burglars it's hardware failure.

Ouch! That's the problem with logical volumes or volume groups spanning several drives - more points of failure...

The particular volume manager does not have some kind of off-line repair or data salvage tool?

Sorry for not being of any help.

Yes, multiple drives leaves you open to multiple failures. I didn't go with RAID as I couldn't afford to implement it at the time.

I've managed to salvage the /etc /usr /var /lib and /root directories. The only thing I've lost is /home and the videos directory. Luckily all my really important stuff is backed up on DVD or on the iBook. Sadly I've lost all my video, which was so large it made it nigh on impossible to back up in any reasonable sense.

I'm now thinking 3x200GB drives in RAID5 with LVM2 on top in external caddies running off an EPIA itx board.

Andy, try recovering you data with R-Studio www.r-tt.com
I have used it many times without any failure to recover yet

ouch, no fun.. I never use LVM for non-raid user data anymore.. it's ok for OS stuff, because it can be esily replaced.. but user data MUST be on raid for me now..

Personaly, I'm working on saving/building a new disk server for my home.. 5x 300GB SATA and a 3ware controler.. Mmmm.. 1TB in my house.. lots of room for FLACs and VOBs

Once you have RAID5 why do you need LVM anymore?

Doesn't RAID 5 effectively give one big virtual drive that you simply create one standard partition (if that's what you want) across?

Certainly that's how I hope the Dell Server with hardware RAID I just ordered works.

Isn't LVM a way to get around not having to grow raid 5 partitions? I mean you can create 1 raid 5 array then add another raid 5 array in the future without destryoing the original data?

Yes, it was the ability to grow filesystems without disturbing existing data that I liked.

Technically of course LVM doesn't allow you to grow filesystems. It allows you to grow drives (volume groups in LVM-speak).

You still need special separate tools to grow and shrink filesystems such as ReiserFS and EXT2/3.

Yes, if you want to split hairs. You resize the partition and then resize the filesystem to suit.

I was trying to inform others reading as much as anything.

Suppose so, although I'd imagine most people who aren't aware of LVM would've read the first post and gone elsewhere.

I don't think that's splitting hairs. It's often easy to increase the size of a partition (for example, on a plain disk, delete the partition 2 and mark partition 1 to now go to the former end of partition 2) , but you have to have complex tools that understand the filesystem at its lowest level in order to increase filesystem size, and many people, even professionals, can forget that distinction -- that partitions and filesystems are not the same thing. I've spent many hours of my life telling that to (admittedly, not very good) Unix admins.

Oh well, that's me told then....

Sorry. I'm in a pissy mood apparently -- tooth pain'll do that to you.

From my investigation last year, expanding most filesystems and LVM groups is easy. And supported in code. The Linux RAID stuff on the other hand had big red flashing warnings around all the expansion stuff saying not to use it except to test the code.

LVM is also better at handling hardware RAID expansion then a raw filesystem or software RAID layered on top. I run an array at work on a fibre attached Smart Array with LVM. I can expand it, let the hardware finish it, then get around to expanding the LVM and filesystem with little to no user interruption.