mysql-fabric is a set of tools to setup resiliend and scalable mysql infrastructures.
You can create fabric groups (a set of replicated servers) with automatic failover and various policies.
#mysqlfabric group create mycluster
#mysqlfabric group add mycluster db-1:3306
#mysqlfabric group add mycluster db-2:3306
#mysqlfabric group add mycluster db-3:3306
And now pick a master: fabric will configure replication on all the nodes
#mysqlfabric group promote mycluster --slave_id DB_1_ID
Now, unless db-1 is a blank page, you’re likely to get an error 🙁
Fabric is trying to replicate ALL the changes happened on db-1 since its creation (included “CREATE USER root …”) to all slaves.
The solution is to
1 – get the last transaction id used for configuration;
2- tell to the slaves to skip everything until then.
It is done via
-- stop replication first, and reset what have been done until now (hopefully nothing ;)
-- tell the slave to skip the first 10 transactions from the server with id 9f36...
SET @@GLOBAL.GTID_PURGED = '9f367fff-d91e-11e4-8ffe-0242ac110017:1-10';
-- now restart the slave and check that everything is fine
SHOW SLAVE STATUS \G
I just found an issue in the oracle agent for rhcs. If you’re curious, check out here on github.
Essentially existing processes were searched via ps | grep | awk instead of ps | grep.
While grep returns nonzero if nothing matches, awk always returns zero, so the agent always waits the timeout before stopping the resource.
After fixing the script in /usr/share/cluster/ reloading the configuration causes the following error
# cman_tool -r version
/usr/share/cluster/cluster.rng:2027: element define: Relax-NG parser error : Some defines for ORACLEDB needs the combine attribute
Relax-NG schema /usr/share/cluster/cluster.rng failed to compile
cman_tool: Not reloading, configuration is not valid
After reading https://access.redhat.com/site/solutions/549963 I just noted that the backup copy of the oracle agent was disturbing the RHCS.
The following chmod seemed to do the trick.
#chmod -x /usr/share/cluster/oracledb.sh-2014-05-26
With lvm you can create clustered volumes allowing different nodes to mount different lvs on the same vg.
The standard workflow of creating partitions and vgs is:
parted /dev/mapper/datadisk mklabel gpt mkpart 1p "1 -1";
vgcreate vg_xml /dev/mapper/datadiskp1
vgchange -c y vg_xml
If you get this error creating the LV
# lvcreate -n lv_xml vg_xml -l +100%FREE
Error locking on node bar-coll-mta-02: Volume group for uuid not found: gFyARW80mUikvaZafzYz773pLBWqc8etOgVrimSit4OmC98c1cIT0qfZfY3tZRxQ
Failed to activate new LV.
That’s because one of the cluster nodes can’t see the newly created volume.
Probably the following will solve