[DRBD-user] Starting up in degraded mode

drbd at bobich.net drbd at bobich.net
Sat Feb 9 16:29:41 CET 2008

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

Anuj Singh wrote:

>> 1) Would it come up correctly if both peers were available and 
>> accessible?
> allow-two-primaries;
>> 2) Is there a standard way of ensuring that if the 2nd node is not
>> accessible after some timeout (e.g. 10-30 seconds), the current node 
>> sets the local instance as primary and create the device node?
> yes. use heartbeat
> http://www.linux-ha.org/GettingStarted
>> 3) Is there a sane way to handle the condition where both nodes come up
>> individually and only then the connection is restored? Obviously, the
>> disks would not be consistent, but they would both be working by that
>> point. Resyncing the BD underneath GFS would probably trash whichever
>> node's data is being overwritten. Is there a method available to 
>> prevent this split-brain condition? One option I can see is to not 
>> sync. GFS would try to mount, notice the other node up but not using 
>> it's journal, and cluster would end up fencing one node. It'd be a race 
>> on which one gets fenced, but that isn't a huge problem.
>             after-sb-0pri discard-younger-primary;
>             after-sb-1pri discard-secondary;
>             after-sb-2pri call-pri-lost-after-sb;
> go threw man pages.

I did, but I am still having a problem. When I only have 1 node up and 
running, it always comes up with Secondary/Unknown. If I bring it up with:
drbdadm -- --overwrite-data-of-peer primary all
it switches to Primary/Unknown and I can use it. But when I reboot, it 
again comes up with Secondary/Unknown. Is there a way to make it come up 
as Primary when the other node is "Unknown" (inaccessible)?


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