[DRBD-user] strange split-brain problem

Klaus Darilion klaus.mailinglists at pernau.at
Tue Dec 7 12:08:28 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.

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?


> 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.


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