[Linux-HA] DRBD not becoming primary when master node fails

Husemann, Harald Harald.Husemann at materna.de
Mon Jul 20 03:49:35 MDT 2009

Hi all,

I have a 2-node cluster, running Pacemaker (crm_resource version 1.04) 
with heartbeat stack and DRBD 8.3.0 (compiled myself) on two CentOS 5.3 
I've added several resources, DRBDs and other, and I can migrate them 
between the cluster nodes without any problems.
But, when I switch off the master node of one of the DRBD resources, 
DRBD fails to start the DRBD on the remaining node.
I've figured out that the problem is that DRBD is unable to set the 
resource on the remaining node to primary state, since the connection to 
the old primary is lost, and this causes the disk to be in "consistent" 
and not in "UpToDate" state which is necessary for it to become primary.

Googlin' a bit showed up that it's possible to force primary mode by 
using the option "overwrite-data-of-peer" with drbdadm, i. e.:

drbdadm -- --overwerite-data-of-peer primary <rsc>.

(It could be necessary to set the resource to "outdated" before).

I've tried this manually, and it worked - but I'd like Pacemaker to do 
this for me...

I took a look into the drbd resource script, and it seems it does not 
handle this situation - is there a newer version of it which takes care 
of this?


Harald Husemann
Netzwerk- und Systemadministrator
Operation Management Center (OMC)
Information & Communications

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