Re: Reassembling RAID1 after good drive was offline [newbie]

[Robert L Mathews <lists@tigertech.com>]

On 1/1/15 9:40 AM, Aryeh Leib Taurog wrote:

> I recently made a RAID1 array from a couple of extra usb drives:
> 
> $ mdadm --create --metadata 1.2 --verbose /dev/md/backup --level=mirror -n2 /dev/sd[cd]2

These are sdc2 and sdd2. Okay.


> Personalities : [raid1] 
> md126 : active (auto-read-only) raid1 sdc2[0]
>       943587136 blocks super 1.2 [2/1] [U_]
>       
> md127 : active (auto-read-only) raid1 sdd2[1]
>       943587136 blocks super 1.2 [2/1] [_U]

Still sdc2 and sdd2, although now in two arrays.


> AFAIK both drives are healthy, but since that happened, it refuses to 
> assemble them both in the array:
> 
> $ mdadm --assemble --force /dev/md/backup /dev/sd[db]2
> mdadm: ignoring /dev/sdb2 as it reports /dev/sdd2 as failed

Now you're working on sdb2 and sdd2. Is that intentional? Did sdc2
become sdb2 after a restart or something?


> Is there any way to put the array back together without having to 
> resync?

You should collect more data about what array each partition thinks it's
a member of, etc., before you try anything else. People can probably
help more if you report the output of these to the list:

 mdadm --detail /dev/md*
 mdadm --examine /dev/sd*

-- 
Robert L Mathews, Tiger Technologies, http://www.tigertech.net/