[Pacemaker] split brain in drbd dual primary setup

[unni krishnan]

Ok, one more doubt. How heartbeat + pacemaker is going to detect that
the drbd is in stand alone state. There is no cluster partition. Only
drbd is disconnected.


On Mon, Dec 7, 2009 at 4:40 PM, Andrew Beekhof <andrew at beekhof.net> wrote:
> On Sun, Dec 6, 2009 at 8:31 PM, unni krishnan <unnikrishnan.a at gmail.com> wrote:
>> Hi,
>>
>> We are using a cluster setup something like :
>>
>> http://picasaweb.google.com/lh/photo/e_uAYjG-8nh7oRZzXDp5HA?feat=directlink
>>
>> We are using
>>
>> OpenVZ for Virtualization
>> DRBD with ocfs2 in dual primary mode
>> heartbeat + pacemaker for HA
>>
>> Currently I have not added the drbd in pacemaker. But added the VPS as
>> resources in pacemaker, so that the VPS can fail over or fail back.
>>
>> My question is, if I remove the cross over cable that connects the
>> drbd then the two server will run in
>>
>> Primary/Unknown state and since the heartbeat connection which is
>> through another cable is not broken, the VPS will run in two nodes.
>>
>> So the data written to two drdb devices in two nodes are different and
>> it is not possible to discard data in any node. What is the better
>> solution for this problem. Please give some hints, thanks :-)
>
> In a word, fencing.
> You need to configure a stonith resource and set the stonith-enabled
> option to true.
>
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-- 
Regards,
Unni