[linux-lvm] Every now and then LVM is not recognized - LVM2 on RAID10
exxs.net - matevz sernc-urban
ms at exxs.net
Thu Jul 24 15:36:48 UTC 2008
Lars Ellenberg schrieb:
> On Wed, Jul 23, 2008 at 02:07:32PM +0200, exxs.net - matevz sernc-urban wrote:
>>
>> i am running into a very interesting situation today, that our LVM
>> metadata is recognized only sometimes. LVM was running fine for some
>> weeks and now from today on running pvscan 10 times one after another i
>> get about 4 positive and 6 negative results (its somehow a coincidence
>> that LVM is recognized).
>>
...
>>
>> Any hints?
>>
>> Where should it look regarding "/dev/md2: No label detected" vs.
>> "/dev/md2: lvm2 label detected"??
>>
>> It seems like RAID-10 is not sync'ed well maybe? But, mdstat reports all
>> disks are up.
>
> just a shot in the dark:
>
> for dev in /dev/sd{a,b,c,d}5; do
> md5=$(dd if=$dev iflag=direct bs=1M count=1 | md5sum)
> echo "$dev: $md5"
> done
this is a RAID 10,f2 (with 2 far copies)
so the starting order of blocks is different on all 4 hdd's (and
therefore all four md5's are different).
>
> echo check > /sys/block/md2/md/sync_action
>
i did this, and it finished without any failures - all disks are up and
sync'ed again. RAID is therefore not a possible problem.
i must add that the logical volumes are in use and working. i just
really do not want to reboot the machine as i suppose they couldn't be
brought up again.
Any other hints of why sometimes i get "/dev/md2: No label detected" vs.
"/dev/md2: lvm2 label detected"?
thanks in advance for any possible hints
mat
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