[Pacemaker] Slave does not start after failover: Mysql circular replication and master-slave resources

[Andreas Kurz]

Hello Attila,

... see below ...

On 12/15/2011 02:42 PM, Attila Megyeri wrote:
> Hi All,
> 
>  
> 
> Some time ago I exchanged a couple of posts with you here regarding
> Mysql active-active HA.
> 
> The best solution I found so  far was the Mysql multi-master
> replication, also referred to as circular replication.
> 
>  
> 
> Basically I set up two nodes, both were capable of the master role, and
> the changes were immediately propagated to the other node.
> 
>  
> 
> But still I wanted to have a M/S approach, to have a RW master and a RO
> slave – mainly because I prefer to have a signle master VIP where my
> apps can connect to.
> 
>  
> 
> (In the first approach I configured a two node clone, and the master IP
> was always bound to one of the nodes)
> 
>  
> 
> I applied the following configuration:
> 
>  
> 
> node db1 \
> 
>         attributes IP="10.100.1.31" \
> 
>         attributes standby="off"
> db2-log-file-db-mysql="mysql-bin.000021" db2-log-pos-db-mysql="40730"
> 
> node db2 \
> 
>         attributes IP="10.100.1.32" \
> 
>         attributes standby="off"
> 
> primitive db-ip-master ocf:heartbeat:IPaddr2 \
> 
>         params lvs_support="true" ip="10.100.1.30" cidr_netmask="8"
> broadcast="10.255.255.255" \
> 
>         op monitor interval="20s" timeout="20s" \
> 
>         meta target-role="Started"
> 
> primitive db-mysql ocf:heartbeat:mysql \
> 
>         params binary="/usr/bin/mysqld_safe" config="/etc/mysql/my.cnf"
> datadir="/var/lib/mysql" user="mysql" pid="/var/run/mysqld/mysqld.pid"
> socket="/var/run/mysqld/mysqld.sock" test_passwd="XXXXX"
> 
>         test_table="replicatest.connectioncheck" test_user="slave_user"
> replication_user="slave_user" replication_passwd="XXXXX"
> additional_parameters="--skip-slave-start" \
> 
>         op start interval="0" timeout="120s" \
> 
>         op stop interval="0" timeout="120s" \
> 
>         op monitor interval="30" timeout="30s" OCF_CHECK_LEVEL="1" \
> 
>         op promote interval="0" timeout="120" \
> 
>         op demote interval="0" timeout="120"
> 
> ms db-ms-mysql db-mysql \
> 
>         meta notify="true" master-max="1" clone-max="2"
> target-role="Started"
> 
> colocation db-ip-with-master inf: db-ip-master db-ms-mysql:Master
> 
> property $id="cib-bootstrap-options" \
> 
>         dc-version="1.1.5-01e86afaaa6d4a8c4836f68df80ababd6ca3902f" \
> 
>         cluster-infrastructure="openais" \
> 
>         expected-quorum-votes="2" \
> 
>         stonith-enabled="false" \
> 
>         no-quorum-policy="ignore"
> 
> rsc_defaults $id="rsc-options" \
> 
>         resource-stickiness="0"
> 
>  
> 
>  
> 
> The setup works in the basic conditions:
> 
> ·         After the “first” startup, nodes start up as slaves, and
> shortly after, one of them is promoted to master.
> 
> ·         Updates to the master are replicated properly to the slave.
> 
> ·         Slave accepts updates, which is Wrong, but I can live with
> this – I will allow connect to the Master VIP only.
> 
> ·         If I stop the slave for some time, and re-start it, it will
> catch up with the master shortly and get into sync.
> 
>  
> 
> I have, however a serious issue:
> 
> ·         If I stop the current master, the slave is promoted, accepts
> RW queries, the Master IP is bound to it – ALL fine.
> 
> ·         BUT – when I want to bring the other node online, it simply
> shows: Stopped (not installed)
> 
>  
> 
> Online: [ db1 db2 ]
> 
>  
> 
> db-ip-master    (ocf::heartbeat:IPaddr2):       Started db1
> 
> Master/Slave Set: db-ms-mysql [db-mysql]
> 
>      Masters: [ db1 ]
> 
>      Stopped: [ db-mysql:1 ]
> 
>  
> 
> Node Attributes:
> 
> * Node db1:
> 
>     + IP                                : 10.100.1.31
> 
>     + db2-log-file-db-mysql             : mysql-bin.000021
> 
>     + db2-log-pos-db-mysql              : 40730
> 
>     + master-db-mysql:0                 : 3601
> 
> * Node db2:
> 
>     + IP                                : 10.100.1.32
> 
>  
> 
> Failed actions:
> 
>     db-mysql:0_monitor_30000 (node=db2, call=58, rc=5, status=complete):
> not installed
> 

Looking at the RA (latest from git) I'd say the problem is somewhere in
the check_slave() function. Either the check for replication errors or
for a too high slave lag ... though on both errors you should see the
log. entries.

Regards,
Andreas

-- 
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http://www.hastexo.com/now


>  
> 
>  
> 
> I checked the logs, and could not find a reason why the slave at db2 is
> not started.
> 
> Any IDEA Anyone ?
> 
>  
> 
>  
> 
> Thanks,
> 
> Attila
> 
> 
> 
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