I brought back the 2 externals, which have had mkfs run on them, but
maybe the extra superblocks will help (doubt it, but couldn't hurt)
root@dhcp128:/media# mdadm -E /dev/sd[a-z]
mdadm: No md superblock detected on /dev/sda.
/dev/sdb:
Magic : a92b4efc
Version : 00.90.00
UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
Creation Time : Wed Mar 25 21:04:08 2009
Raid Level : raid6
Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
Raid Devices : 6
Total Devices : 6
Preferred Minor : 0
Update Time : Tue Mar 31 23:08:02 2009
State : clean
Active Devices : 5
Working Devices : 6
Failed Devices : 1
Spare Devices : 1
Checksum : a4fbb93a - correct
Events : 8430
Chunk Size : 64K
Number Major Minor RaidDevice State
this 6 8 16 6 spare /dev/sdb
0 0 8 0 0 active sync /dev/sda
1 1 8 64 1 active sync /dev/sde
2 2 8 32 2 active sync /dev/sdc
3 3 8 48 3 active sync /dev/sdd
4 4 0 0 4 faulty removed
5 5 8 80 5 active sync /dev/sdf
6 6 8 16 6 spare /dev/sdb
/dev/sdc:
Magic : a92b4efc
Version : 00.90.00
UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
Creation Time : Wed Mar 25 21:04:08 2009
Raid Level : raid6
Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
Raid Devices : 6
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 12 11:31:47 2009
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 2
Spare Devices : 0
Checksum : a59452db - correct
Events : 580158
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 32 2 active sync /dev/sdc
0 0 8 0 0 active sync /dev/sda
1 1 0 0 1 faulty removed
2 2 8 32 2 active sync /dev/sdc
3 3 8 48 3 active sync /dev/sdd
4 4 0 0 4 faulty removed
5 5 8 96 5 active sync /dev/sdg
/dev/sdd:
Magic : a92b4efc
Version : 00.90.00
UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
Creation Time : Wed Mar 25 21:04:08 2009
Raid Level : raid6
Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
Raid Devices : 6
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 12 11:31:47 2009
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 2
Spare Devices : 0
Checksum : a59452ed - correct
Events : 580158
Chunk Size : 64K
Number Major Minor RaidDevice State
this 3 8 48 3 active sync /dev/sdd
0 0 8 0 0 active sync /dev/sda
1 1 0 0 1 faulty removed
2 2 8 32 2 active sync /dev/sdc
3 3 8 48 3 active sync /dev/sdd
4 4 0 0 4 faulty removed
5 5 8 96 5 active sync /dev/sdg
/dev/sde:
Magic : a92b4efc
Version : 00.90.00
UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
Creation Time : Wed Mar 25 21:04:08 2009
Raid Level : raid6
Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
Raid Devices : 6
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 12 11:31:47 2009
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 2
Spare Devices : 0
Checksum : a5945321 - correct
Events : 580158
Chunk Size : 64K
Number Major Minor RaidDevice State
this 5 8 96 5 active sync /dev/sdg
0 0 8 0 0 active sync /dev/sda
1 1 0 0 1 faulty removed
2 2 8 32 2 active sync /dev/sdc
3 3 8 48 3 active sync /dev/sdd
4 4 0 0 4 faulty removed
5 5 8 96 5 active sync /dev/sdg
/dev/sdf:
Magic : a92b4efc
Version : 00.90.00
UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
Creation Time : Wed Mar 25 21:04:08 2009
Raid Level : raid6
Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
Raid Devices : 6
Total Devices : 5
Preferred Minor : 0
Update Time : Wed Apr 8 11:13:32 2009
State : clean
Active Devices : 5
Working Devices : 5
Failed Devices : 1
Spare Devices : 0
Checksum : a5085415 - correct
Events : 97276
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 80 1 active sync /dev/sdf
0 0 8 0 0 active sync /dev/sda
1 1 8 80 1 active sync /dev/sdf
2 2 8 32 2 active sync /dev/sdc
3 3 8 48 3 active sync /dev/sdd
4 4 0 0 4 faulty removed
5 5 8 96 5 active sync /dev/sdg
mdadm: No md superblock detected on /dev/sdg.
On Thu, Dec 17, 2009 at 8:39 AM, Majed B. <majedb@xxxxxxxxx> wrote:
> You can't copy and change bytes to identify disks.
>
> To check which disks belong to an array, do this:
> mdadm -E /dev/sd[a-z]
>
> The disks that you get info from belong to the existing array(s).
>
> In the first email you sent you included an examine output for one of
> the disks that listed another disk as a spare (sdb). The output of
> examine should shed more light.
>
> On Thu, Dec 17, 2009 at 5:15 PM, Carl Karsten <carl@xxxxxxxxxxxxxxxxx> wrote:
>> On Thu, Dec 17, 2009 at 4:35 AM, Majed B. <majedb@xxxxxxxxx> wrote:
>>> I have misread the information you've provided, so allow me to correct myself:
>>>
>>> You're running a RAID6 array, with 2 disks lost/failed. Any disk loss
>>> after that will cause data loss since you have no redundancy (2 disks
>>> died).
>>
>> right - but I am not sure if data loss has occurred, where data is the
>> data being stored on the raid, not the raid metadata.
>>
>> My guess is I need to copy the raid superblock from one of the other
>> disks (say sdb), find the byets that identify the disk and change from
>> sdb to sda.
>>
>>>
>>> I believe it's still possible to reassemble the array, but you only
>>> need to remove the MBR. See this page for information:
>>> http://www.cyberciti.biz/faq/linux-how-to-uninstall-grub/
>>> dd if=/dev/null of=/dev/sdX bs=446 count=1
>>>
>>> Before proceeding, provide the output of cat /proc/mdstat
>>
>> root@dhcp128:~# cat /proc/mdstat
>> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
>> [raid4] [raid10]
>> unused devices: <none>
>>
>>
>>> Is the array currently running degraded or is it suspended?
>>
>> um, not running, not sure I would call it suspended.
>>
>>> What happened to the spare disk assigned?
>>
>> I don't understand.
>>
>>> Did it finish resyncing
>>> before you installed grub on the wrong disk?
>>
>> I think so.
>>
>> I am fairly sure I could assemble the array before I installed grub.
>>
>>>
>>> On Thu, Dec 17, 2009 at 8:21 AM, Majed B. <majedb@xxxxxxxxx> wrote:
>>>> If your other disks are sane and you are able to run a degraded array, then
>>>> you can remove grub using dd then re-add the disk to the array.
>>>>
>>>> To clear the first 1MB of the disk:
>>>> dd if=/dev/zero of=/dev/sdx bs=1M count=1
>>>> Replace sdx with the disk name that has grub.
>>>>
>>>> On Dec 17, 2009 6:53 AM, "Carl Karsten" <carl@xxxxxxxxxxxxxxxxx> wrote:
>>>>
>>>> I took over a box that had 1 ide boot drive, 6 sata raid drives (4
>>>> internal, 2 external.) I believe the 2 externals were redundant, so
>>>> could be removed. so I did, and mkfs-ed them. then I installed
>>>> ubuntu to the ide, and installed grub to sda, which turns out to be
>>>> the first sata. which would be fine if the raid was on sda1, but it
>>>> is on sda, and now the raid wont' assemble. no surprise, and I do
>>>> have a backup of the data spread across 5 external drives. but before
>>>> I abandon the array, I am wondering if I can fix it by recreating
>>>> mdadm's metatdata on sda, given I have sd[bcd] to work with.
>>>>
>>>> any suggestions?
>>>>
>>>> root@dhcp128:~# mdadm --examine /dev/sd[abcd]
>>>> mdadm: No md superblock detected on /dev/sda.
>>>> /dev/sdb:
>>>> Magic : a92b4efc
>>>> Version : 00.90.00
>>>> UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
>>>> Creation Time : Wed Mar 25 21:04:08 2009
>>>> Raid Level : raid6
>>>> Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
>>>> Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
>>>> Raid Devices : 6
>>>> Total Devices : 6
>>>> Preferred Minor : 0
>>>>
>>>> Update Time : Tue Mar 31 23:08:02 2009
>>>> State : clean
>>>> Active Devices : 5
>>>> Working Devices : 6
>>>> Failed Devices : 1
>>>> Spare Devices : 1
>>>> Checksum : a4fbb93a - correct
>>>> Events : 8430
>>>>
>>>> Chunk Size : 64K
>>>>
>>>> Number Major Minor RaidDevice State
>>>> this 6 8 16 6 spare /dev/sdb
>>>>
>>>> 0 0 8 0 0 active sync /dev/sda
>>>> 1 1 8 64 1 active sync /dev/sde
>>>> 2 2 8 32 2 active sync /dev/sdc
>>>> 3 3 8 48 3 active sync /dev/sdd
>>>> 4 4 0 0 4 faulty removed
>>>> 5 5 8 80 5 active sync
>>>> 6 6 8 16 6 spare /dev/sdb
>>>> /dev/sdc:
>>>> Magic : a92b4efc
>>>> Version : 00.90.00
>>>> UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
>>>> Creation Time : Wed Mar 25 21:04:08 2009
>>>> Raid Level : raid6
>>>> Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
>>>> Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
>>>> Raid Devices : 6
>>>> Total Devices : 4
>>>> Preferred Minor : 0
>>>>
>>>> Update Time : Sun Jul 12 11:31:47 2009
>>>> State : clean
>>>> Active Devices : 4
>>>> Working Devices : 4
>>>> Failed Devices : 2
>>>> Spare Devices : 0
>>>> Checksum : a59452db - correct
>>>> Events : 580158
>>>>
>>>> Chunk Size : 64K
>>>>
>>>> Number Major Minor RaidDevice State
>>>> this 2 8 32 2 active sync /dev/sdc
>>>>
>>>> 0 0 8 0 0 active sync /dev/sda
>>>> 1 1 0 0 1 faulty removed
>>>> 2 2 8 32 2 active sync /dev/sdc
>>>> 3 3 8 48 3 active sync /dev/sdd
>>>> 4 4 0 0 4 faulty removed
>>>> 5 5 8 96 5 active sync
>>>> /dev/sdd:
>>>> Magic : a92b4efc
>>>> Version : 00.90.00
>>>> UUID : 8d0cf436:3fc2d2ef:93d71b24:b036cc6b
>>>> Creation Time : Wed Mar 25 21:04:08 2009
>>>> Raid Level : raid6
>>>> Used Dev Size : 1465137408 (1397.26 GiB 1500.30 GB)
>>>> Array Size : 5860549632 (5589.06 GiB 6001.20 GB)
>>>> Raid Devices : 6
>>>> Total Devices : 4
>>>> Preferred Minor : 0
>>>>
>>>> Update Time : Sun Jul 12 11:31:47 2009
>>>> State : clean
>>>> Active Devices : 4
>>>> Working Devices : 4
>>>> Failed Devices : 2
>>>> Spare Devices : 0
>>>> Checksum : a59452ed - correct
>>>> Events : 580158
>>>>
>>>> Chunk Size : 64K
>>>>
>>>> Number Major Minor RaidDevice State
>>>> this 3 8 48 3 active sync /dev/sdd
>>>>
>>>> 0 0 8 0 0 active sync /dev/sda
>>>> 1 1 0 0 1 faulty removed
>>>> 2 2 8 32 2 active sync /dev/sdc
>>>> 3 3 8 48 3 active sync /dev/sdd
>>>> 4 4 0 0 4 faulty removed
>>>> 5 5 8 96 5 active sync
>>>>
>>>> --
>>>> Carl K
>>>> --
>>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
>>>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>>>
>>>
>>>
>>>
>>> --
>>> Majed B.
>>>
>>>
>>
>>
>>
>> --
>> Carl K
>>
>
>
>
> --
> Majed B.
>
>
--
Carl K
--
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