[Pacemaker] need cluster-wide variables

shashi shashidhara.td at huawei.com
Wed Jan 4 23:59:13 EST 2012

> Its not something we had planned, this is the first time anyone has asked.
> I'd be happy to help point someone on your side in the right
> direction, but if I have to do all of it, you might be waiting a
> while.
> Can you explain the use case further?  Maybe there is another option.

Here is our scenario:
We have a stateful(tri-state) service. (Master, Preferred Master, Slave).
We want to achieve a tree like structure where in root node is master and leaf 
nodes are slaves and the in-between nodes are Preferred Masters (There could 
be more than one preferred master. (Basically this is done to reduce the load 
from the Master, Otherwise all Slaves need to synchronize from Master).

              /    \
      Pre-Master   Pre-Master
     /       |        \
Slave     Slave       Slave

Master synchronizes its data with the attached Preferred Masters and Slaves 
synchronizes its data from attached Prefered Master. 
We want one of the Pre-Master to take over as master in case of master 
instance failure (simultaneously tree restructuring is required) and one of 
the slave to take over the Pre-Master role when one of the Pre-Master Fails.

So we have two probable options:
1. An work around to achieve this tri-state efficiently without changing 
pacemaker internals.
2. Modify pacemaker to add this tri-state feature.

So please suggest how to go about it.

Thanks & Regards

More information about the Pacemaker mailing list