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I have run into a strange problem with a DRBD resource migrating
master role from one node to the other. 3-node cluster, Pacemaker
v1.1.9, Corosync v1.4.5, DRBD 8.3.11. Both Pacemaker and Corosync
are built from source. Two of the nodes are running DRBD resources
between them in simple single-master relationships. <br>
<br>
The nodes are called c3, c4, and c5; c5 is location-constrained to
never receive DRBD resource clones. I have a drbd resource called
ms_drbd-p_dummy1, and a dummy resource called p_dummy1. The
resource is colocated with the drbd master, and ordered such that
master is promoted before the resource is started. The config
generally follows accepted online examples (see below).<br>
<br>
When c3 is master, I attempt to migrate to c4 by issuing "resource
migrate p_dummy1". I see a fleeting FAILED notice in crm_mon for
c3, then the cluster then starts into this cycle where it keeps
bringing the relevant DRBD resource up and down very quickly.
Syslog shows the connection being setup and torn-down over and
over. The up-down cycle is broken by issuing "resource unmigrate
p_dummy1" after which c4 becomes DRBD master and c3 its slave. That
is to say, the migration works but only after the unmigrate is
issued. Migrating from c4 to c3 works every time.<br>
<br>
Putting either node into standby works fine, resources migrate
without issue in that case. I have fencing enabled and tested, but
it's not being called into action here. I also tried re-creating my
DRBD resource and resyncing, with no change to the results. I can
manually shift either node to primary using drbdadm while the
resource is unmanaged by Pacemaker. I have also duplicated this
behavior with one of my other DRBD resources and a second dummy
resource. Finally, I confirmed this between a new drbd and dummy
resource set between c4 and c5 (where c4->c5 transition fails
until unmigrate is issued, but c5->c4 migrate works fine).<br>
<br>
An attempt to manually demote ms_drbd-aoe1 resulted in Pacemaker
reporting a failure, even though /proc/drbd subsequently showed both
nodes in Secondary.<br>
<br>
This syslog fragment shows the attempt, failure, unmigrate and the
eventual success of migration:
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Key configuration elements:<br>
<br>
primitive p_drbd-aoe1 ocf:linbit:drbd \<br>
params drbd_resource="aoe1" \<br>
op start interval="0" timeout="5m" \<br>
op promote interval="0" timeout="90s" \<br>
op demote interval="0" timeout="90s" \<br>
op stop interval="0" timeout="3m" \<br>
op monitor interval="20" role="Slave" timeout="20" \<br>
op monitor interval="10" role="Master" timeout="20"<br>
<br>
primitive p_dummy1 ocf:heartbeat:Dummy<br>
<br>
ms ms_drbd-aoe1 p_drbd-aoe1 \<br>
meta master-max="1" notify="true" clone-max="2"
master-node-max="1" clone-node-max="1" target-role="Started"
is-managed="true"<br>
<br>
colocation colo_dummy inf: p_dummy1 ms_drbd-aoe1:Master<br>
order o_dummy inf: ms_drbd-aoe1:promote p_dummy1:start<br>
<br>
Any ideas?<br>
<br>
Thanks!!<br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">--
Thank you!
Matthew O'Connor
(GPG Key ID: 55F981C4)
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