[Drbd-dev] DRBD8: Split-brain if primary and syncTarget

[Goswin von Brederlow]

"Montrose, Ernest" <Ernest.Montrose at stratus.com> writes:

> :o="urn:schemas-microsoft-com:office:office"
> xmlns:w="urn:schemas-microsoft-com:office:word"
> xmlns="http://www.w3.org/TR/REC-html40">
>
> Hi all,:p>
>
> :p> 
>
> We are seeing an issue with split brain if one node is syncing as syncTarget
> while being Primary.:p>
>
> two node A and B.
> * make B primary and the syncTarget
> * Start a sync.
> * ifdown eth1 to break communication
> * ifup eth1.
> * then on the node in standalone "drbdadm connect":p>
>
> We get a split-brain.:p>
>
> :p> 
>
> I think the  problem is that if we are primary and we lose contact from the
> other side
> we generate a new current UUID which causes a Split-Brain next time we
> connect.
> This only happens if we are the sync target and we are primary. Perhaps we
> should not generate a UUID if we were syncing when the disconnect happen.
> Below is a possible patch for this in after_state_ch()::p>

I think the new UUID should be generated the first time there is a
write but not before.

MfG
        Goswin