Mailinglist Archive: opensuse (1264 mails)

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Re: [opensuse] mdadm raid problem
On 06/07/2017 10:32 PM, David C. Rankin wrote:
On 06/07/2017 04:29 PM, Istvan Gabor wrote:
Hello:

I have this problem in openSUSE 13.2. My mdadm version is:

mdadm --version
mdadm - v3.3.1 - 5th June 2014

I have some degraded RAID1 arrays. Before adding back the failed devices
to the arrays I would like to mount the devices independently and compare
their contents.


What do the following show:

# mdadm -D /dev/md101

# mdadm -E /dev/sd[bc]11

and look at /dev/disk/by-id

It sounds like you are attempting to add a drive back to the array that the
array considers failed. The mdadm commands should show what the array thinks
its drives are and what the drives think their mdadm uuids are. Hard to tell.


Sorry to reply to a reply, but before you can add back your failed drive from
an array (I guess /dev/sdc11 is the failed drive and md101 is the array in
this case) you must remove it from the array (e.g. --fail then --remove it),
then you can add it back. For example:

# mdadm /dev/md101 --fail /dev/sdc11 --remove /dev/sdc11

(if it was already failed, it will just report 'set device faulty failed
/dev/sdc11: No such device)

Then you can add it back with:

# mdadm /dev/md101 --add /dev/sdc11

(it should report: 'mdadm: re-added /dev/sdc11')

What is considered the most up to date drive in the array for re-syncing
purposes will be the drive with the largest event count if all other things
are equal.

You can fail, remove and re-add disks to the array without any problem. (you
can do it for fun or for testing) mdadm is quite robust in that regard.

--
David C. Rankin, J.D.,P.E.

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