[ClusterLabs] Master/Slave DRBD not active on asymmetric cluster

[Klaus Wenninger]

Hi!

I guess the collocation with ClusterIP is the culprit.
It leads to the clone not being started where ClusterIP
is not running.
Guess what you'd rather want is a collocation with
just the master-role of the clone.

Regards,
Klaus

On 03/14/2017 03:44 PM, Bruyninckx Kristof wrote:
>
> Hello,
>
>  
>
> Currently I’ve tried to setup a 3 node asymmetric cluster, with the
> 3th node only being used as a tie breaker.
>
>  
>
> monnod01 & monnod02 :
>
> ·        centos 7.3
>
> ·        pacemaker-1.1.15-11.el7_3.2.x86_64,
>
> ·        corosync-2.4.0-4.el7.x86_64
>
> ·        drbd84-utils-8.9.8-1.el7.elrepo.x86_64
>
> ·        PostgreSQL 9.4
>
> monquor:
>
> ·        centos 7.3
>
> ·        pacemaker-1.1.15-11.el7_3.2.x86_64
>
> ·        corosync-2.4.0-4.el7.x86_64
>
> ·        no drbd installed.
>
>  
>
> Now I’ve noticed that the master/slave drbd resource only activates
> the master side and not also the slave side allowing the drbd to
> actually sync between each other. I’ve setup a 2 node cluster, and
> there it works without any issue.
>
> But when I try to do the same, but with a 3th node, and
>
>  
>
> /pcs property set symmetric-cluster=false/
>
>  
>
> For some reason it keeps adding the 3the node as a stopped resource in
> the master slave setup and it doesn’t mention a slave resource.
>
>  
>
> /pcs status/
>
> /Online: [ monnod01 monnod02 monquor ]/
>
> / /
>
> /Full list of resources:/
>
> / /
>
> /ClusterIP      (ocf::heartbeat:IPaddr2):       Started monnod01/
>
> /Master/Slave Set: drbd-demo-resource-clone [drbd-demo-resource]/
>
> /     Masters: [ monnod01 ]/
>
> /     Stopped: [ monquor ]/
>
>  
>
> Resource created with the following
>
>  
>
> /pcs -f drbd_cfg resource create drbd-demo-resource ocf:linbit:drbd
> drbd_resource=drbd-demo op monitor interval=10s/
>
> /pcs -f drbd_cfg resource master drbd-demo-resource-clone
> drbd-demo-resource master-max=1 master-node-max=1 clone-max=2
> clone-node-max=1 notify=true/
>
>  
>
> Even though I’ve used location constraints on the master slave
> resource allowing it only access to the 2 nodes.
>
>  
>
> /[root at monnod01 ~]# pcs constraint/
>
> /  Resource: drbd-demo-resource-clone/
>
> /    Enabled on: monnod01 (score:INFINITY)/
>
> /    Enabled on: monnod02 (score:INFINITY)/
>
>  
>
> The actual failover itself works, so it activates the DRBD disk,
> mounts it and starts up the db service which access the files on this
> drbd disk.
>
> But since the slave drbd is never started, it’ll never actually
> perform the drbd sync between the disks.
>
> What am I missing to actually make the master/slave resource ignore
> the 3 node and startup the master and slave resource ?
>
> Does DRBD need to be installed on the 3th node as well ?
>
>  
>
> I’ve put the complete output of the commands in the attachment of the
> mail.
>
>  
>
> Met vriendelijke groeten / Meilleures salutations / Best regards
>
> *Kristof Bruyninckx*
> *System Engineer*
>
>  
>
>  
>
>
>
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