Hi Kishore
Our system requires deterministic placement of the MASTER and SLAVE.
This is a sample of the idealstate file we're using
{
"id": "Cluster",
"simpleFields":{
"IDEAL_STATE_MODE":"AUTO",
"NUM_PARTITIONS": "1",
"REPLICAS": "2",
"STATE_MODEL_DEF_REF":"MasterSlave"
},
"mapFields":{
},
"listFields":{
"Partition_0" : [ "node_1", "node_2" ]
}
}
In this example, node_1 is the MASTER.
If node_1 dies then node_2 will take over.
But if node_1 then get restarted, it will try to become MASTER again.
We normally keep the died node down to avoid this problem.
But I was hoping for a more elegant solution.
One solution would be for node_1 to come up and realizes that node_2 has taken
over due to the previous failure.
In that case node_1 will decide to remain as a SLAVE node instead.
Should this be done by the Controller instead?
Should I create a new statemodel other than MASTER/SLAVE?
On Mar 31, 2013, at 12:50 AM, kishore g <[email protected]> wrote:
> Hi MIng,
>
> There are couple of ways you can achieve that. Before providing an answer,
> how many partitions do you have. Did you generate the idealstate yourself or
> used Helix to come up with initial idealstate?
>
> The reason old master tries to become a master again is to distribute the
> load among the nodes currently alive. Otherwise the old node that comes back
> will never become a master for any partition and will remain idle until
> another failure happens in the system.
>
> thanks,
> Kishore G
>
>
> On Sat, Mar 30, 2013 at 8:01 PM, Ming Fang <[email protected]> wrote:
> We're using MASTER SLAVE in AUTO model.
> When the MASTER is killed, the failover is working properly as the SLAVE
> transitions to become MASTER.
> However if the failed MASTER is restarted, it will try to become MASTER again.
> This is causing a problem in our business logic.
> Is there a way to prevent the failed instance from becoming MASTER again?
>
