[Pacemaker] Question about Pacemaker master/slave and mysql replication

[Michael Szilagyi]

I'm already using the mysql RA file from
https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/mysql(which
also seems to have replication support in it).

Basically what seems to be happening is that pacemaker detects that the
master has dropped and promotes a slave up to master.  However, it is not
properly reconfiguring the slaves with a CHANGE MASTER TO.  I can see some
lines in the ocf file that relate to changing master but it isn't setting it
up properly.  If I login to the slave and issue a CHANGE MASTER TO ... /
START SLAVE then replication will start up normally again.

Since I can see that the script does allow the master host to get set when
going through set/unset_master I'm hoping it's just something I'm missing
and not a limitation of using Pacemaker to manage the sql replication
cluster.

Hopefully someone can point me at what I am missing.

-Mike.

On Mon, Aug 15, 2011 at 1:56 AM, Dan Frincu <df.cluster at gmail.com> wrote:

> Hi,
>
> On Sat, Aug 13, 2011 at 2:53 AM, Michael Szilagyi <mszilagyi at gmail.com>
> wrote:
> > I'm new to Pacemaker and trying to understand exactly what it can and
> can't
> > do.
> > I currently have a small, mysql master/slave cluster setup that is
> getting
> > monitored within Heartbeat/Pacemaker:  What I'd like to be able to do
> (and
> > am hoping Pacemaker will do) is to have 1 node designated as Master and
> in
> > the event of a failure, automatically promote a slave to master and
> realign
> > all of the existing slaves to be slaves of the newly promoted master.
> >  Currently what seems to be happening, however, is heartbeat correctly
> sees
> > that a node goes down and pacemaker promotes it up to master but the
> > replication is not adjusted so that it is now feeding everyone else.  It
> > seems like this should be possible to do from within Pacemaker but I feel
> > like I'm missing a part of the puzzle.  Any suggestions would be
> > appreciated.
>
> You could try the mysql RA => from
> https://github.com/fghaas/resource-agents/blob/master/heartbeat/mysql
> Last I heard, it had replication support.
>
> HTH.
>
> >
> > Here's an output of my crm configure show:
> > node $id="7deca2cd-9a64-476c-8ea2-372bca859a4f" four \
> > attributes 172.17.0.130-log-file-p_sql="mysql-bin.000013"
> > 172.17.0.130-log-pos-p_sql="632"
> > node $id="9b355ab7-8c81-485c-8dcd-1facedde5d03" three \
> > attributes 172.17.0.131-log-file-p_sql="mysql-bin.000020"
> > 172.17.0.131-log-pos-p_sql="106"
> > primitive p_sql ocf:heartbeat:mysql \
> > params config="/etc/mysql/my.cnf" binary="/usr/bin/mysqld_safe"
> > datadir="/var/lib/mysql" \
> > params pid="/var/lib/mysql/novaSQL.pid"
> socket="/var/run/mysqld/mysqld.sock"
> > \
> > params max_slave_lag="120" \
> > params replication_user="novaSlave" replication_passwd="nova" \
> > params additional_parameters="--skip-external-locking
> > --relay-log=novaSQL-relay-bin --relay-log-index=relay-bin.index
> > --relay-log-info-file=relay-bin.info" \
> > op start interval="0" timeout="120" \
> > op stop interval="0" timeout="120" \
> > op promote interval="0" timeout="120" \
> > op demote interval="0" timeout="120" \
> > op monitor interval="10" role="Master" timeout="30" \
> > op monitor interval="30" role="Slave" timeout="30"
> > primitive p_sqlIP ocf:heartbeat:IPaddr2 \
> > params ip="172.17.0.96" \
> > op monitor interval="10s"
> > ms ms_sql p_sql \
> > meta target-role="Started" is-managed="true"
> > location l_sqlMaster p_sqlIP 10: three
> > location l_sqlSlave1 p_sqlIP 5: four
> > property $id="cib-bootstrap-options" \
> > dc-version="1.0.9-unknown" \
> > cluster-infrastructure="Heartbeat" \
> > stonith-enabled="false" \
> > no-quorum-policy="ignore" \
> > last-lrm-refresh="1313187103"
> >
> > Thanks!
> > -Mike.
> > _______________________________________________
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> > http://oss.clusterlabs.org/mailman/listinfo/pacemaker
> >
> > Project Home: http://www.clusterlabs.org
> > Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
> > Bugs:
> >
> http://developerbugs.linux-foundation.org/enter_bug.cgi?product=Pacemaker
> >
> >
>
>
>
> --
> Dan Frincu
> CCNA, RHCE
>
> _______________________________________________
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>
> Project Home: http://www.clusterlabs.org
> Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf
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>
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