I have a problem with my home server setup. The problem is that sometimes, but really rarely, it reverts (for a lack of a better term) all my data back to an earlier state (somewhere between months and weeks earlier).
The setup is a 4TB ext4 on a Software RAID 5 with 3 disks running on an Ubuntu 12.04 (linux 3.2). Samba serves files of that partition.
/proc/mdstat tells me that the array is healthy
smartclt -H /dev/sdX says PASSED for all devices. I tried to find something in the logs but I couldn't find anything suspicious.
Last time the error occurred I rebooted the server whilst using files on the shear however
fsck didn't find any errors.
The nature of the error baffles me. Since ext is not a copy on write file system, I would have assumed something like this is impossible. If you can think of any diagnostics I can run, please don't hesitate.
I guess the question is what happened to my data and how can I stop it from happening again?
— edit —
OK I found the error:
The problem had nothing to do with ext4. The problem was the way I mounted the device.
I have the raid 5 for my data and a raid 0 with an backup. But the way I mounted this at startup was not 100% stable; sometimes the backup was mounted as the main.
# main RAID array /dev/md126p1 /media/Main ext4 defaults 0 0
# definitions of existing MD arrays ARRAY /dev/md/Main metadata=1.2 UUID=c2ccbd00:ce414404:0ee05911:eebe2832 ARRAY /dev/md/Backup metadata=1.2 UUID=b4973c41:e735e1c0:29e8be4b:4fe7c007 name=:Backup
Whoever can answer me this small question gets the bounty: What is the best way to mount the backup and the main in a guaranteed stable way.
Version : 1.2 Creation Time : Sun Jun 19 15:45:35 2011 Raid Level : raid0 Array Size : 3907021824 (3726.03 GiB 4000.79 GB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Sun Jun 19 15:45:35 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Chunk Size : 512K Name : :Backup UUID : b4973c41:e735e1c0:29e8be4b:4fe7c007 Events : 0 Number Major Minor RaidDevice State 0 8 33 0 active sync /dev/sdc1 1 8 81 1 active sync /dev/sdf1
Version : 1.2 Creation Time : Sun Jun 12 02:13:25 2011 Raid Level : raid5 Array Size : 3907021568 (3726.03 GiB 4000.79 GB) Used Dev Size : 1953510784 (1863.01 GiB 2000.40 GB) Raid Devices : 3 Total Devices : 3 Persistence : Superblock is persistent Intent Bitmap : Internal Update Time : Mon Jan 28 19:00:45 2013 State : active Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 128K Name : :Neue RAID-Anordnung UUID : c2ccbd00:ce414404:0ee05911:eebe2832 Events : 17846 Number Major Minor RaidDevice State 0 8 49 0 active sync /dev/sdd1 1 8 1 1 active sync /dev/sda1 3 8 65 2 active sync /dev/sde1