[CentOS] C7, mdadm issues

Wed Jan 30 08:45:58 UTC 2019
Alessandro Baggi <alessandro.baggi at gmail.com>

Il 29/01/19 20:42, mark ha scritto:
> Alessandro Baggi wrote:
>> Il 29/01/19 18:47, mark ha scritto:
>>> Alessandro Baggi wrote:
>>>> Il 29/01/19 15:03, mark ha scritto:
>>>>
>>>>> I've no idea what happened, but the box I was working on last week
>>>>> has a *second* bad drive. Actually, I'm starting to wonder about
>>>>> that particulare hot-swap bay.
>>>>>
>>>>> Anyway, mdadm --detail shows /dev/sdb1 remove. I've added
>>>>> /dev/sdi1...
>>>>> but see both /dev/sdh1 and /dev/sdi1 as spare, and have yet to find
>>>>> a reliable way to make either one active.
>>>>>
>>>>> Actually, I would have expected the linux RAID to replace a failed
>>>>> one with a spare....
> 
>>>> can you report your raid configuration like raid level and raid devices
>>>> and the current status from /proc/mdstat?
>>>>
>>> Well, nope. I got to the point of rebooting the system (xfs had the
>>> RAID
>>> volume, and wouldn't let go; I also commented out the RAID volume.
>>>
>>> It's RAID 5, /dev/sdb *also* appears to have died. If I do
>>> mdadm --assemble --force -v /dev/md0  /dev/sd[cefgdh]1 mdadm: looking for
>>> devices for /dev/md0 mdadm: /dev/sdc1 is identified as a member of
>>> /dev/md0, slot 0.
>>> mdadm: /dev/sdd1 is identified as a member of /dev/md0, slot -1.
>>> mdadm: /dev/sde1 is identified as a member of /dev/md0, slot 2.
>>> mdadm: /dev/sdf1 is identified as a member of /dev/md0, slot 3.
>>> mdadm: /dev/sdg1 is identified as a member of /dev/md0, slot 4.
>>> mdadm: /dev/sdh1 is identified as a member of /dev/md0, slot -1.
>>> mdadm: no uptodate device for slot 1 of /dev/md0
>>> mdadm: added /dev/sde1 to /dev/md0 as 2
>>> mdadm: added /dev/sdf1 to /dev/md0 as 3
>>> mdadm: added /dev/sdg1 to /dev/md0 as 4
>>> mdadm: no uptodate device for slot 5 of /dev/md0
>>> mdadm: added /dev/sdd1 to /dev/md0 as -1
>>> mdadm: added /dev/sdh1 to /dev/md0 as -1
>>> mdadm: added /dev/sdc1 to /dev/md0 as 0
>>> mdadm: /dev/md0 assembled from 4 drives and 2 spares - not enough to
>>> start the array.
>>>
>>> --examine shows me /dev/sdd1 and /dev/sdh1, but that both are spares.
>> Hi Mark,
>> please post the result from
>>
>> cat /sys/block/md0/md/sync_action
> 
> There is none. There is no /dev/md0. mdadm refusees, saying that it's lost
> too many drives.
> 
>        mark
> 
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I suppose that your config is 5 drive and 1 spare with 1 drive failed.
It's strange that your spare was not used for resync.
Then you added a new drive but it does not start because it marks the 
new disk as spare and you have a raid5 with 4 devices and 2 spares.

First I hope that you have a backup for all your data and don't run some 
exotic command before backupping your data. If you can't backup your 
data, it's a problem.

Have you tried to remove the last added device sdi1 and restart the raid 
and force to start a resync?

Have you tried to remove this 2 devices and re-add only the device that 
will be usefull for resync?  Maybe you can set 5 devices for your raid 
and not 6, if it works (after resync) you can add your spare device 
growing your raid set.

Reading on google many users use --zero-superblock before re-add the device.

Other user reassemble the raid using --assume-clean but I don't know 
what effect it will produces

Hope that this helps.