[DRBD-user] split brain detected when switching back to the 2node cluster from the DR node

Pierre LEBRECH pierre.lebrech at laposte.net
Wed Aug 5 10:00:07 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hello,

Thank you for your answer.

Yes, I can use these commands to handle split-brains.

BUT, the thing I don't understand is why I get split-brain in this scenario.

I think it's not normal to get such a split-brain when I manually switch HA services from node3 to the 2node cluster.

If we look at the end of step 2 (below), we can see that everynode is connected and UpToDate (node1 point of view).

It's only when I start heartbeat on node1 and 2 (normal way after the switch over) that I get this split-brain.

There is something wrong somewhere but what?




guohuai li a écrit :
> Hi,
> 
>  
> 
> There are several items such as below in /etc/drbd.conf.
> 
> You may need to study it.
> 
>  
> 
> My DRBD is 8.3.0.
> 
> It works well.
> 
>  
> 
> edward
> 
>  
> 
> #after-sb-0pri disconnect;
> 
> after-sb-0pri "discard-older-primary";
> 
>  
> 
> #after-sb-1pri disconnect;
> 
> after-sb-1pri discard-secondary; 
>  
>> Date: Tue, 4 Aug 2009 18:58:15 +0200
>> From: pierre.lebrech at laposte.net
>> To: drbd-user at lists.linbit.com
>> Subject: [DRBD-user] split brain detected when switching back to the
> 2node cluster from the DR node
>>
>> Hello,
>>
>> I always get a split brain when I switch the HA services back to the
> 2node cluster from my DR node.
>>

STEP 1 :

>> Here are the steps I follow :
>>
>> - HA services are on the DR node
>> - I stop these HA services
>> - I umount the data
>>
>> The state of DRBD on node3 is as follow :
>>
>> ------------------------------
>> version: 8.3.2 (api:88/proto:86-90)
>> GIT-hash: dd7985327f146f33b86 d4bff5ca8c94234ce840e build by
> root at hcns1, 2009-08-04 09:41:09
>>
>> 1: cs:WFConnection ro:Primary/Unknown ds:UpToDate/DUnknown C r----
>> ns:0 nr:34083396 dw:34084032 dr:68168163 al:12 bm:2094 lo:0 pe:0 ua:0
> ap:0 ep:1 wo:f oos:208
>> ------------------------------
>>

STEP 2 :

>> Then, on node1 :
>>
>> - drbdadm primary r0
>> - I start the HA IP
>> - drbdadm --stacked up r0-U
>>
>> At this point, every thing is OK. Here is the output of cat /proc/drbd :
>>
>> ------------------------------
>> version: 8.3.2 (api:88/proto:86-90)
>> GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by
> root at hans1, 2009-08-04 09:43:39
>> 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r----
>> ns:13706 nr:174 dw:15096 dr:102401147 al:30 bm:2170 lo:0 pe:0 ua:0
> ap:0 ep:1 wo:f oos:0
>> 1: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r----
>> ns:0 nr:244 dw:244 dr:416 al:0 b m:9 lo:0 pe:0 ua:0 ap:0 ep:1 wo:d oos:0
>> ------------------------------
>>
>> Then, I set all things back (reset) :
>>

STEP 3 :

>> on node1 :
>>
>> - drbdadm --stacked down r0-U
>> - drbdadm secondary r0
>> - I stop the HA IP
>>
>> The state on node1 is as follow :
>>
>> ------------------------------
>> version: 8.3.2 (api:88/proto:86-90)
>> GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by
> root at hans1, 2009-08-04 09:43:39
>> 0: cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate C r----
>> ns:13707 nr:174 dw:15097 dr:102401147 al:30 bm:2186 lo:0 pe:0 ua:0
> ap:0 ep:1 wo:f oos:0
>> 1: cs:Unconfigured
>> ------------------------------
>>
>> on node3, I type these commands to reset the state :
>>
>> - drbdadm secondary r0-U
>>

STEP 4 :

>> Then, on node1 and node2, I start heartbeat normally.
>>
>>
>>
>> Well, each time I follo w theses steps, node3 gets a split-brain.
>>
>> Where is the problem?
>>
>>
>>
>>
>> context : 3-node cluster, every node connected, HA services on node1,
> DRBD version 8.3.2 on linux 2.6.30.
>>
>> _______________________________________________
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>> drbd-user at lists.linbit.com
>> http://lists.linbit.com/mailman/listinfo/drbd-user
> 
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