[DRBD-user] split-brain after trying to verify?

Lars Ellenberg lars.ellenberg at linbit.com
Fri Oct 23 13:59:49 CEST 2009

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

On Fri, Oct 23, 2009 at 03:21:49PM +0400, Michael Tokarev wrote:
> Hello.
> Yesterday I installed drbd for the first time, to see
> how it works.  And almost immediately come across a
> problem where I don't see an immediate solution.
> I followed the howto, built a resource, syncronized
> it, created a filesystem on it, switched roles
> (pri/sec) between two hosts, made it primary on
> two nodes, did some writes etc.  So far so good,
> it all worked just fine.
> Next, I added "verify-alg sha1;" on both sides
> and ran `drbdadm adjust' on both nodes.  Next
> I ran 'drbdadm verify'.
> There was no activity on the resource during
> this time (between editing and running verify,
> at least).
> Now, drbd declared a split-brain situation,
> and refuses to work.
> I've no idea where the split-brain come from,
> since the content should be identical on both
> sides, and verify should've prove it.

You adjusted network parameters (verify-alg), which we still cannot do
while keeping the connection.
So your first "adjust" to add the verify-alg had to
disconnect ; then reconnect with new parameters.

Don't do that while both are Primary.

> I also don't have an idea what to do next, ie,
> how to resolve the "conflict".  Restarting stuff
> does not help.

There is a section about recovering from split brain
in the DRBD User's Guide

: Lars Ellenberg                
: LINBIT HA-Solutions GmbH
: DRBD®/HA support and consulting    http://www.linbit.com

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