[mythtv-users] OT-RAID 5 failure. MDADM experts? Seagate 1.5TB failure

Jake Anderson yahoo at vapourforge.com
Thu Dec 18 09:58:59 UTC 2008


Mark wrote:
> Hello,
> I have been bitten by a firmware issue on the new Seagate 1.5TB drives.  
> Before the firmware update on the drive, they go offline. I have now 
> updated the firmeware on the drives, but two went off-line in a 4 drive 
> RAID 5. 
>
> Two are degraded now and I am unable to start the array.
> Details.  /dev/sdb,c,d,e built previously with mdadm and was working fine.
> Now, I am unable to assemble ( even with force ) my /dev/md0 as two are 
> failed.
>
> Here is the mdadm examine on the 4 drives:
>
>  mdadm -E /dev/sd[b-e]1
> mdadm: No md superblock detected on /dev/sdb1.
> /dev/sdc1:
>           Magic : a92b4efc
>         Version : 0.90.00
>            UUID : e0dc7a82:21d0f971:f1bb1dea:a305e5a8
>   Creation Time : Thu Dec 11 09:08:21 2008
>      Raid Level : raid5
>   Used Dev Size : 1465135872 (1397.26 GiB 1500.30 GB)
>      Array Size : 4395407616 (4191.79 GiB 4500.90 GB)
>    Raid Devices : 4
>   Total Devices : 4
> Preferred Minor : 0
>
>     Update Time : Sun Dec 14 12:17:42 2008
>           State : active
>  Active Devices : 4
> Working Devices : 4
>  Failed Devices : 0
>   Spare Devices : 0
>        Checksum : 2a871ffd - correct
>          Events : 953875
>
>          Layout : left-symmetric
>      Chunk Size : 256K
>
>       Number   Major   Minor   RaidDevice State
> this     1       8       49        1      active sync   /dev/sdd1
>
>    0     0       8       33        0      active sync   /dev/sdc1
>    1     1       8       49        1      active sync   /dev/sdd1
>    2     2       8       65        2      active sync   /dev/sde1
>    3     3       8       17        3      active sync   /dev/sdb1
> /dev/sdd1:
>           Magic : a92b4efc
>         Version : 0.90.00
>            UUID : e0dc7a82:21d0f971:f1bb1dea:a305e5a8
>   Creation Time : Thu Dec 11 09:08:21 2008
>      Raid Level : raid5
>   Used Dev Size : 1465135872 (1397.26 GiB 1500.30 GB)
>      Array Size : 4395407616 (4191.79 GiB 4500.90 GB)
>    Raid Devices : 4
>   Total Devices : 4
> Preferred Minor : 0
>
>     Update Time : Sun Dec 14 12:25:06 2008
>           State : clean
>  Active Devices : 2
> Working Devices : 2
>  Failed Devices : 2
>   Spare Devices : 0
>        Checksum : 2a95b019 - correct
>          Events : 953892
>
>          Layout : left-symmetric
>      Chunk Size : 256K
>
>       Number   Major   Minor   RaidDevice State
> this     2       8       65        2      active sync   /dev/sde1
>
>    0     0       8       33        0      active sync   /dev/sdc1
>    1     1       0        0        1      faulty removed
>    2     2       8       65        2      active sync   /dev/sde1
>    3     3       0        0        3      faulty removed
> /dev/sde1:
>           Magic : a92b4efc
>         Version : 0.90.00
>            UUID : e0dc7a82:21d0f971:f1bb1dea:a305e5a8
>   Creation Time : Thu Dec 11 09:08:21 2008
>      Raid Level : raid5
>   Used Dev Size : 1465135872 (1397.26 GiB 1500.30 GB)
>      Array Size : 4395407616 (4191.79 GiB 4500.90 GB)
>    Raid Devices : 4
>   Total Devices : 4
> Preferred Minor : 0
>
>     Update Time : Sun Dec 14 12:25:06 2008
>           State : clean
>  Active Devices : 2
> Working Devices : 2
>  Failed Devices : 2
>   Spare Devices : 0
>        Checksum : 2a95aff5 - correct
>          Events : 953892
>
>          Layout : left-symmetric
>      Chunk Size : 256K
>
>       Number   Major   Minor   RaidDevice State
> this     0       8       33        0      active sync   /dev/sdc1
>
>    0     0       8       33        0      active sync   /dev/sdc1
>    1     1       0        0        1      faulty removed
>    2     2       8       65        2      active sync   /dev/sde1
>    3     3       0        0        3      faulty removed
>
>
> If I try to assemble with the 3 (  mdadm -A /dev/md0 /dev/sd[c-e]1 ) I 
> get the results below:
>
> mdadm: cannot open device /dev/sde1: Device or resource busy
> mdadm: /dev/sde1 has no superblock - assembly aborted
>
>
> Ideas on what to try?
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>   
Format the lot and start over?
you might not be able to recover it without going over the top.
If the disks were in use at the time of failure then critical chunks of 
data might have been changed between disks.

IE the array is in an inconsistent state and theres no real way to 
reconcile that.

Only other thought I seem to remember something about needing to pass 
mdadm an option when rebuilding to tell it to make it into a new array 
or some such, might only have been when you moved the array to a 
different host though.


When you sort it all out, use storage groups rather than raid, you will 
get much better performance and probably disk life, the seek load is 
going to be drastically reduced.


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