Hello Here is my story: I recently migrated a server from Windows to Ubuntu 9.04. I formatted all disks with ext4. The server has 5 disks: three SCSI (9GB for /, 2x18GB for /data/small and /home) and two IDE (2x300GB). I put the IDE disks in a RAID0: each had a single partition with type set to "fd", and the entire resulting device (/dev/md0) was formatted with ext4 as: mkfs.ext4 -b 4096 -E stride=16 /dev/md0 All was well until a power outage that left the filesystem on /dev/md0 unmountable (the others were fine after an fsck). I made a backup of the corrupted array to another disk and ran fsck, but it ended up in an infinite loop. After some unsuccessful tinkering, I restored the backup and found out that large portions of the group descriptor table are filled with random junk. Moreover, all backup superblocks are either corrupted or zeroed, and I found partial copies of an identically corrupted table at various weird offsets (including 176888, 600344, 1036536, 1462520, 1887256 and 5326832); neither of these copies were preceded by anything resembling a superblock. Here is a copy of first 39 blocks of the corrupted disk: http://tweenk.artfx.pl/super.bin The group descriptors that are not filled with random junk all follow a simple pattern, but filling the group descriptor table with with an extension of it didn't yield anything interesting. A smartctl check revealed that one of the disks forming the array has Reallocated_Sector_Ct = 17 and Reallocated_Event_Count = 1 (coincidentally, 17 is also the number of backup superblocks this device should have), the other has zero; however, this doesn't explain the massive corruption. Regards, Krzysztof Kosiński PS Please CC replies to me as I'm not subscribed -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
