[DRBD-user] strange split-brain problem

Klaus Darilion klaus.mailinglists at pernau.at
Tue Dec 7 19:02:53 CET 2010

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


Just for the records - I think I found the problem.

I recently changed the IP address of the server but there was an entry 
in /etc/hosts which still pointed to the old IP address. From reading 
the docs that shouldn't matter as the host directive in drbd.conf is 
compared with "uname -n" and uname -n was still correctly displaying the 
proper hostname.

(this was not the IP address used for DRBD communcication, DRDB uses a 
dedicated private subnet)

But apparently it mattered as after fixing the hostname's IP address in 
/etc/hosts there problems were gone.


Am 07.12.2010 12:08, schrieb Klaus Darilion:
> Hi Felix!
> Thanks for you answers.
> Am 07.12.2010 10:09, schrieb Felix Frank:
>> On 12/06/2010 06:08 PM, Klaus Darilion wrote:
>> ...
>>> So, why again resynchronizing almost 500Mb although the partition is not
>>> used at all (just mounted in a domU).
>> It does this based on the activity log. See
>> http://www.drbd.org/users-guide/s-activity-log.html for the details.
> I was just surprised that it had to sync 500MByte although there were
> now writes on the partition.
>>> When I tried to manually attach the device I got error messages:
>>> "Split-Brain detected, dropping connection".
>> Split brain happens when the following happen in order:
>> 1. you loose connection while having a primary
>> 2. the other node becomes primary while still disconnected
> This is why I do not understand how I got to a split brain. I do not use
> a cluster manager - switching from secondary to primary is done only
> manually. Node A was primary, Node B was secondary. The config states
> that "become-primary-on nodeA". So, node B was never switched to
> primary. Thus, from my understanding it should be impossible to get
> split-brain as nodeB was always secondary.
>>> So, suddenly this one device is not connected anymore. All the other
>>> drbd devices are still connected and working fine - only this single
>>> device is making problems, although it has identical configuration.
>> So this is the device with the splitbrain condition?
> Yes
>> You will need to resolve that, refer to
>> http://www.drbd.org/users-guide/s-resolve-split-brain.html
> I did that now and try to reproduce the problem.
>> Have you made sure that your /etc/rc6.d and rc0.d have "stop" links to
>> the drbd init script? We have seen splitbrain upon reboot as well, and I
>> believe that missing init links were the reason.
> stop symlinks are present.
> regards
> Klaus
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user

More information about the drbd-user mailing list