Thanks BoB. That got me running (after I cleaned up some of my own mess).
The problem I had running your commands was that, in following some
other directions, I'd removed and recreated the partition on /dev/sdc.
The new one I created wasn't the correct size (too small).
Resolved that by;
sgdisk --backup=table /dev/sdb
sgdisk --load-backup=table /dev/sdc
sgdisk -G /dev/sdc
Once the --re-add command completed successfully, I was able to 'mdadm
--assemble --scan'
The array is rebuilding now;
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdc1[1] sdb1[0] sde1[4] sdd1[2]
8790405120 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [U_UU]
[>....................] recovery = 3.3% (97349984/2930135040)
finish=545.3min speed=86578K/sec
bitmap: 9/22 pages [36KB], 65536KB chunk
unused devices: <none>
Thanks for the help, BoB and Marc
On Mon, Jun 2, 2014 at 1:12 PM, B-o-B De Mars <mr.chew.baka at gmail.com> wrote:
> On 6/1/2014 6:15 PM, Mark Mitchell wrote::
>
>> I built my first RAID array about a week ago, kinda vaguely
>> understanding what I'm doing. 4 3 TB drives in a RAID 5. It's been
>> working fine, and I've been slowly filling it up.
>>
>> Took the machine apart today to upgrade case cooling and power supply.
>> When I brought it back up, I got this in the boot messages;
>>
>> md/raid:md0: raid level 5 active with 3 out of 4 devices, algorithm 2
>>
>> My 1st thought was that I didn't get everything hooked up (I had to
>> disconnect most of the drives to get the power connections on the
>> board), several reboots later, I'd confirmed that the system was
>> seeing all the drives;
>>
>> root at debian:/var/log# lsblk
>> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
>> sda 8:0 0 931.5G 0 disk
>> ├─sda1 8:1 0 14G 0 part /
>> ├─sda2 8:2 0 37.3G 0 part [SWAP]
>> └─sda3 8:3 0 880.3G 0 part /home
>> sdb 8:16 0 2.7T 0 disk
>> └─sdb1 8:17 0 2.7T 0 part
>> └─md0 9:0 0 8.2T 0 raid5
>> └─md0p1 259:0 0 8.2T 0 md /srv/media
>> sdc 8:32 0 2.7T 0 disk
>> └─sdc1 8:33 0 2.7T 0 part
>> sdd 8:48 0 2.7T 0 disk
>> └─sdd1 8:49 0 2.7T 0 part
>> └─md0 9:0 0 8.2T 0 raid5
>> └─md0p1 259:0 0 8.2T 0 md /srv/media
>> sde 8:64 0 2.7T 0 disk
>> └─sde1 8:65 0 2.7T 0 part
>> └─md0 9:0 0 8.2T 0 raid5
>> └─md0p1 259:0 0 8.2T 0 md /srv/media
>> sr0 11:0 1 7.3G 0 rom
>>
>> So, it looks like the partition on sdc isn't being seen as a raid
>> partition anymore.
>>
>> FWIW;
>> root at debian:/var/log# cat /proc/mdstat
>> Personalities : [raid6] [raid5] [raid4]
>> md0 : active raid5 sdb1[0] sde1[4] sdd1[2]
>> 8790405120 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3]
>> [U_UU]
>> bitmap: 4/22 pages [16KB], 65536KB chunk
>>
>> unused devices: <none>
>>
>> So, what's my next step? Looks to me like I need to recreate sdc1 as
>> a raid partition, then regrow the array. Is this correct?
>>
>> In the meantime, I'm reading what I can and copying data off the
>> array. Nothing critical, but it'd be annoying to lose.
>>
>> Let me know if I left out required information.
>>
>
> do a mdadm --detail /dev/md0 (or md* for all), and look for the failed
> device\partition#
>
> *Adjust the below to your config*
>
> First fail the drive
> sudo mdadm /dev/md0 -f /dev/sdc1fdisk /dev/sdb
>
> Then remove the drive
> sudo mdadm /dev/md0 -r /dev/sdc1
>
> To re-add an out of sink partition
> I just "sudo mdadm --manage --re-add /dev/md0 /dev/sdc1"
>
> To check rebuilt status
>
> watch cat /proc/mdstat
>
> Done.
>
> Good Luck!
>
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