[Pacemaker] MySQL/PostgreSQL HA cluster with Pacemaker

Andrew nitr0 at seti.kr.ua
Fri Nov 2 04:03:25 EDT 2012

On 02/11/12 01:02, Andrew Beekhof wrote:
> On Fri, Nov 2, 2012 at 2:34 AM, Andrew<nitr0 at seti.kr.ua>  wrote:
>> On 01/11/12 03:02, Andrew Beekhof wrote:
>>> On Thu, Nov 1, 2012 at 5:27 AM, Andrew<nitr0 at seti.kr.ua>   wrote:
>>>> Hi all.
>>>> I try to build 1+1 MySQL HA cluster, and currently I'm looking on Percona
>>>> replication manager; other variant - to write own OCF for
>>>> semi-synchronous
>>>> master-slave replication. Also I want to run here PostgreSQL HA DB.
>>>> So I have some questions:
>>>> 1) How pacemaker decides what node should be master, when both nodes
>>>> booting
>>>> after, for ex., power failure? First running node will become a master,
>>>> or
>>>> Pacemaker can wait some time till node, that was a master before crash,
>>>> will
>>>> be running?
>>> We run monitor on both nodes.
>>> This is the chance for the resource agent script to tell us their
>>> preference for being promoted to master.
>>> We then factor that into our decision.
>> Can you explain? Pacemaker doesn't start master resource automatically if
>> slave is booted succesfully and master is still booting/crashed at boot?
> It does, but it first makes sure the failed node isn't running
> anything by fencing it.
So if old master is still booting (for ex., fs check in progress) and 
hasn't running corosync - slave will become a master, and data that 
wasn't replicated to slave will be lost?
This isn't too critical in most cases (except when one node is crashed 
and after some time all nodes will be rebooted due to power failure), 
but is there a possibility to avoid this behavior?

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