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Old 11-06-2012, 06:33 PM   #1
hugodlc
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Registered: Nov 2012
Posts: 1

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Power loss during Raid5 to Raid6 rebuild


Hi, this is my first post as I have spent all last week looking everywhere for a solution to my problem.

Background:
I was in the middle of growing my 7TB Raid 5 Array to a Raid 6 just for safety (as I had a hot spare anyways), when a microsecond power failure killed the process and forced me to reboot.

Upon reboot, the server couldn't mount the Array, and it marked it as Raid 6 with one member syncing but there was no "sync" activity going on, so after searching and trying a few things, I finally managed to get mdadm to rebuild the array, and after rebuild/sync it was supposedly clean.
The problem lies with the Ext4 filesystem inside, it will not mount my data and fsck reports thousands of errors, and all the backup superblocks are no use. (same errors)

I can see the information is still in the Array, as mdadm reports on all the drives:

Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 6975498d:fa4de084:75948791:3876b445
Name : tenoch:1 (local to host tenoch)
Creation Time : Thu Nov 1 17:45:51 2012
Raid Level : raid6
Raid Devices : 6

Avail Dev Size : 3896319671 (1857.91 GiB 1994.92 GB)
Array Size : 7792637952 (7431.64 GiB 7979.66 GB)
Used Dev Size : 3896318976 (1857.91 GiB 1994.92 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : d163e01a:ed0b7ac7:b68cdde1:f1f03208

Update Time : Mon Nov 5 21:27:03 2012
Checksum : 7113ba79 - correct
Events : 9196

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 0
Array State : AAAAAA ('A' == active)

I've tried running photorec to retrieve the data, and it appears to be there and ok, but there's just too much information lost going about it this way. (not to mention having to re-name/date, etc... thousands of files)

Also I'm a bit concerned about letting fsck "correct" all those thousands of "inconsistencies", to later find that in doing so, now everything is erased.

I'm also trying Raise Data Recovery software but "if" it works... it could take upwards of 40 days to retrieve the data, and I'm sure everything is there, as mdadm reports the array having the information, events and all.

What can I do?

Is there a way to revert back to a raid 5 and maybe the superblocks will match?
Or anything else?

I'm out of ideas.... please help

Thanks!
 
  


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