Re: raid device gone underneath array

[Adam Goryachev <mailinglists@websitemanagers.com.au>]

On 19/10/12 11:01, Marcus Sorensen wrote:
> I've been using software raid to mirror two devices, and recently one
> of the drives went AWOL.
>
> md1 : active raid1 sdm[0] sdc[1](F)
>       12884900728 blocks super 1.2 [2/1] [U_]
>       bitmap: 1/96 pages [4KB], 65536KB chunk
>
> However, md1 froze, and in looking at the logs I saw this:
>
> Oct 18 17:47:48 sys kernel: md: cannot remove active disk sdc from md1 ...
> Oct 18 17:47:48 sys kernel: md: cannot remove active disk sdc from md1 ...
>
> [root(marcus)@sanmirror3-01 ~]# mdadm --manage /dev/md1 --remove /dev/sdc
> mdadm: cannot find /dev/sdc: No such file or directory
>
> /dev/sdc was already gone! The /sys/block was already removed, no
> reference to it in /proc/scsi/scsi. So md1 was destined to sit there
> forever. So I rebooted and started up the degraded array.
>
> Using kernel 3.6.2 from kernel.org

I've also had this problem, I think the kernel notices the device is
gone, and removes it before MD notices the problem and removes it from
the array. I managed to resolve this without a reboot by manually
creating the device in /dev/sdc1 or whatever, and then doing mdadm
--manage /dev/md0 --remove /dev/sdc1

Regards,
Adam


-- 
Adam Goryachev
Website Managers
www.websitemanagers.com.au