[Users] split brain in drbd dual primary setup

Philipp Wehrheim flipstar at gmx.net
Mon Dec 7 02:14:53 EST 2009


Hey Unni,

unni krishnan schrieb:

your questions are more focused on heartbeat /pacemaker
so you may want to ask your questions on those lists ...

> OpenVZ for Virtualization
> DRBD with ocfs2 in dual primary mode

Why are you using active/active and a cluster-fs???
this makes things more complex than they have to be.

> 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.

You definitely want to add drbd to your pacemaker setup!

> 
> 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 :-)

Make sure that heartbeat and drbd use the same link (if you have the resources
use NIC-bonding!!!) further more you should be using a stonith device (*device* _not_ ssh) to be
really sure only one node survives an error.

Personally I'm running a OpenVZ setup [1],
which uses a script called mbhave to setup the heartbeat/drbd ressources.
You may want to have a look at it

cheers
flip

[1] http://forum.openvz.org/index.php?t=msg&goto=32740&


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