[DRBD-user] Dual-Primary Split Brain

Digimer linux at alteeve.com
Thu Sep 30 20:35:12 CEST 2010

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

On 10-09-30 10:39 AM, raveenpl wrote:
> Hello,
> I would like to have Primary/Primary cluster. The most wondering in this
> solution is for me how to cope with split-brain sitaution. 
> I know that they are to two ways to fence nodes (on resource level and using
> STONITH) - but how they work in dual-primary mode? Maybe somebody could give
> step-by-step example?
> Cheers
> RaveenPL

I use it with Red Hat Cluster Services and their fence daemon. I've got
an in-progress How-To, but it's not finished enough to post publicly
here. If you're okay with that, and are interested, send me an email
off-list and I'll send you the link.

The setup is:

- RAID Level 1 on either node.
- Cluster built using RHCS Cluster Stable 3 on Fedora 13 (until RHEL 6
is released).
- DRBD across the two nodes.
- CLVM on top of the DRBD resource.

If your question is more to do with recovering from split brain, then
it's as follows. Note that in this case, I chose 'Node 1' to be the most
up to date node. You'll need to make that decision yourself in the real

-= Node 1		-= Node2
modprobe drbd		modprobe drbd
drbdadm attach r0	drbdadm attach r0
			drbdadm invalidate r0
drbdadm connect r0	drbdadm connect r0
drbdadm primary r0	drbdadm primary r0

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