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cloudon7281 09-21-2010 11:21 AM

Recovering lost files on LVM2 + RAID5 following disk failure & re-assembly?

Through finding a use for old hardware I'm now running Fedora 10 on a crappy old box with
- 1 x internal HD hosting the OS
- 4 x external USB drives, 2x500GB with single partitions, 2x1TB each partitioned into 2x500GB
- 2 x RAID partitions
- 1 RAID5, consisting of a 500GB partition from each drive
- 1 RAID1, consisting of the remaining 2 500GB partitions from the 1TB drive
- LVM2 on top; one PV per RAID, one VG, 5 LVs.

This has been happily acting as a backup-cum-DLNA media server for my family.

Recently one of the 1TB disks failed, and I had a power cut which rebooted the box. After some faff (the drives acquired different partitions on reboot) I've re-assembled and re-started both RAID arrays, and activated LVM on top. So far so good, but I've found that some of my LVs have lost recent files (i.e. no files exist with creation dates more recent than the last vgcfgbackup was taken), though some others are fully up-to-date.

I'm pretty sure I haven't done anything which ought to affect the LVM metadata since the last backup (I use the system-config-lvm GUI, which I believe automatically takes back-ups), but my guess is that the affected LVs are missing a record of some physical extents?

fsck reports clean on the affected LVs, and there's nothing in lost+found. I also haven't touched any of the data on any of the LVs since re-assembly.

Googling finds lots of the problems I had re-assembling and re-starting the arrays, but I can't find anything matching the recent file loss.

Any ideas on how to recover the lost files?

thanks in advance


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