[Pacemaker] drbd under pacemaker - always get split brain

Andreas Kurz andreas at hastexo.com
Wed Jul 11 07:40:49 UTC 2012 

On 07/11/2012 09:23 AM, Nikola Ciprich wrote:
>>> It really really looks like Pacemaker is too fast when promoting to
>>> primary ... before the connection to the already up second node can be
>>> established.
>>
>> Do you mean we're violating a constraint?
>> Or is it a problem of the RA returning too soon?
> dunno, I tried older drbd userspaces to check if it's not problem
> of newer RA, to no avail...
> 
>>
>>> I see in your logs you have DRBD 8.3.13 userland  but
>>> 8.3.11 DRBD module installed ... can you test with 8.3.13 kernel module
>>> ... there have been fixes that look like addressing this problem.
> tried 8.3.13 userspace + 8.3.13 module (on top of 3.0.36 kernel), unfortunately same result..
> 
>>>
>>> Another quick-fix, that should also do: add a start-delay of some
>>> seconds to the start operation of DRBD
>>>
>>> ... or fix your after-split-brain policies to automatically solve this
>>> special type of split-brain (with 0 blocks to sync).
> I'll try that, although I'd not like to use this for production :)

Well, I'd expect that to be safer as your current configuration ...
discard-zero-changes will never overwrite data automatically .... have
you tried adding the start-delay to DRBD start operation? I'm curious if
that is already sufficient for your problem.

Regards,
Andreas

> 
>>>
>>> Best Regards,
>>> Andreas
>>>
>>> --
>>> Need help with Pacemaker?
>>> http://www.hastexo.com/now
>>>
>>>>
>>>> thanks for Your time.
>>>> n.
>>>>
>>>>
>>>>>
>>>>> Regards,
>>>>> Andreas
>>>>>
>>>>> --
>>>>> Need help with Pacemaker?
>>>>> http://www.hastexo.com/now
>>>>>
>>>>>>
>>>>>> thanks a lot in advance
>>>>>>
>>>>>> nik
>>>>>>
>>>>>>
>>>>>> On Sun, Jul 08, 2012 at 12:47:16AM +0200, Andreas Kurz wrote:
>>>>>>> On 07/02/2012 11:49 PM, Nikola Ciprich wrote:
>>>>>>>> hello,
>>>>>>>>
>>>>>>>> I'm trying to solve quite mysterious problem here..
>>>>>>>> I've got new cluster with bunch of SAS disks for testing purposes.
>>>>>>>> I've configured DRBDs (in primary/primary configuration)
>>>>>>>>
>>>>>>>> when I start drbd using drbdadm, it get's up nicely (both nodes
>>>>>>>> are Primary, connected).
>>>>>>>> however when I start it using corosync, I always get split-brain, although
>>>>>>>> there are no data written, no network disconnection, anything..
>>>>>>>
>>>>>>> your full drbd and Pacemaker configuration please ... some snippets from
>>>>>>> something are very seldom helpful ...
>>>>>>>
>>>>>>> Regards,
>>>>>>> Andreas
>>>>>>>
>>>>>>> --
>>>>>>> Need help with Pacemaker?
>>>>>>> http://www.hastexo.com/now
>>>>>>>
>>>>>>>>
>>>>>>>> here's drbd resource config:
>>>>>>>> primitive drbd-sas0 ocf:linbit:drbd \
>>>>>>>>     params drbd_resource="drbd-sas0" \
>>>>>>>>     operations $id="drbd-sas0-operations" \
>>>>>>>>     op start interval="0" timeout="240s" \
>>>>>>>>     op stop interval="0" timeout="200s" \
>>>>>>>>     op promote interval="0" timeout="200s" \
>>>>>>>>     op demote interval="0" timeout="200s" \
>>>>>>>>     op monitor interval="179s" role="Master" timeout="150s" \
>>>>>>>>     op monitor interval="180s" role="Slave" timeout="150s"
>>>>>>>>
>>>>>>>> ms ms-drbd-sas0 drbd-sas0 \
>>>>>>>>    meta clone-max="2" clone-node-max="1" master-max="2" master-node-max="1" notify="true" globally-unique="false" interleave="true" target-role="Started"
>>>>>>>>
>>>>>>>>
>>>>>>>> here's the dmesg output when pacemaker tries to promote drbd, causing the splitbrain:
>>>>>>>> [  157.646292] block drbd2: Starting worker thread (from drbdsetup [6892])
>>>>>>>> [  157.646539] block drbd2: disk( Diskless -> Attaching )
>>>>>>>> [  157.650364] block drbd2: Found 1 transactions (1 active extents) in activity log.
>>>>>>>> [  157.650560] block drbd2: Method to ensure write ordering: drain
>>>>>>>> [  157.650688] block drbd2: drbd_bm_resize called with capacity == 584667688
>>>>>>>> [  157.653442] block drbd2: resync bitmap: bits=73083461 words=1141930 pages=2231
>>>>>>>> [  157.653760] block drbd2: size = 279 GB (292333844 KB)
>>>>>>>> [  157.671626] block drbd2: bitmap READ of 2231 pages took 18 jiffies
>>>>>>>> [  157.673722] block drbd2: recounting of set bits took additional 2 jiffies
>>>>>>>> [  157.673846] block drbd2: 0 KB (0 bits) marked out-of-sync by on disk bit-map.
>>>>>>>> [  157.673972] block drbd2: disk( Attaching -> UpToDate )
>>>>>>>> [  157.674100] block drbd2: attached to UUIDs 0150944D23F16BAE:0000000000000000:8C175205284E3262:8C165205284E3263
>>>>>>>> [  157.685539] block drbd2: conn( StandAlone -> Unconnected )
>>>>>>>> [  157.685704] block drbd2: Starting receiver thread (from drbd2_worker [6893])
>>>>>>>> [  157.685928] block drbd2: receiver (re)started
>>>>>>>> [  157.686071] block drbd2: conn( Unconnected -> WFConnection )
>>>>>>>> [  158.960577] block drbd2: role( Secondary -> Primary )
>>>>>>>> [  158.960815] block drbd2: new current UUID 015E111F18D08945:0150944D23F16BAE:8C175205284E3262:8C165205284E3263
>>>>>>>> [  162.686990] block drbd2: Handshake successful: Agreed network protocol version 96
>>>>>>>> [  162.687183] block drbd2: conn( WFConnection -> WFReportParams )
>>>>>>>> [  162.687404] block drbd2: Starting asender thread (from drbd2_receiver [6927])
>>>>>>>> [  162.687741] block drbd2: data-integrity-alg: <not-used>
>>>>>>>> [  162.687930] block drbd2: drbd_sync_handshake:
>>>>>>>> [  162.688057] block drbd2: self 015E111F18D08945:0150944D23F16BAE:8C175205284E3262:8C165205284E3263 bits:0 flags:0
>>>>>>>> [  162.688244] block drbd2: peer 7EC38CBFC3D28FFF:0150944D23F16BAF:8C175205284E3263:8C165205284E3263 bits:0 flags:0
>>>>>>>> [  162.688428] block drbd2: uuid_compare()=100 by rule 90
>>>>>>>> [  162.688544] block drbd2: helper command: /sbin/drbdadm initial-split-brain minor-2
>>>>>>>> [  162.691332] block drbd2: helper command: /sbin/drbdadm initial-split-brain minor-2 exit code 0 (0x0)
>>>>>>>>
>>>>>>>> to me it seems to be that it's promoting it too early, and I also wonder why there is the
>>>>>>>> "new current UUID" stuff?
>>>>>>>>
>>>>>>>> I'm using centos6, kernel 3.0.36, drbd-8.3.13, pacemaker-1.1.6
>>>>>>>>
>>>>>>>> could anybody please try to advice me? I'm sure I'm doing something stupid, but can't figure out what...
>>>>>>>>
>>>>>>>> thanks a lot in advance
>>>>>>>>
>>>>>>>> with best regards
>>>>>>>>
>>>>>>>> nik
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
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>>>>>>>>
>>>>>>>> Project Home: http://www.clusterlabs.org
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>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
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>>>>>>>
>>>>>>> Project Home: http://www.clusterlabs.org
>>>>>>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>>>>>> Bugs: http://bugs.clusterlabs.org
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
>>>>>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>>>>>>
>>>>>> Project Home: http://www.clusterlabs.org
>>>>>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>>>>> Bugs: http://bugs.clusterlabs.org
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>> _______________________________________________
>>>>> Pacemaker mailing list: Pacemaker at oss.clusterlabs.org
>>>>> http://oss.clusterlabs.org/mailman/listinfo/pacemaker
>>>>>
>>>>> Project Home: http://www.clusterlabs.org
>>>>> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
>>>>> Bugs: http://bugs.clusterlabs.org
>>>>
>>>>
>>>> --
>>>> -------------------------------------
>>>> Ing. Nikola CIPRICH
>>>> LinuxBox.cz, s.r.o.
>>>> 28.rijna 168, 709 00 Ostrava
>>>>
>>>> tel.:   +420 591 166 214
>>>> fax:    +420 596 621 273
>>>> mobil:  +420 777 093 799
>>>> www.linuxbox.cz
>>>>
>>>> mobil servis: +420 737 238 656
>>>> email servis: servis at linuxbox.cz
>>>> -------------------------------------
>>>>
>>>> _______________________________________________
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>>>>
>>>> Project Home: http://www.clusterlabs.org
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>>>> Bugs: http://bugs.clusterlabs.org
>>>>
>>>
>>>
>>>
>>>
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>>>
>>> Project Home: http://www.clusterlabs.org
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>>> Bugs: http://bugs.clusterlabs.org
>>>
>>
>> _______________________________________________
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>>
>> Project Home: http://www.clusterlabs.org
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>> Bugs: http://bugs.clusterlabs.org
>>
> 
> 
> 
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> 
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> 



-- 
Need help with Pacemaker?
http://www.hastexo.com/now


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