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Re: [Linux-cluster] recommended method for changing quorum device



On 05/31/2011 03:35 PM, bergman merctech com wrote:
I've got a 3-node RHCS cluster and the quorum device is on a SAN disk
array that needs to be replaced. The relevent versions are:

       CentOS 5.6 (2.6.18-238.9.1.el5)
       openais-0.80.6-28.el5_6.1
       cman-2.0.115-68.el5_6.3
       rgmanager-2.0.52-9.el5.centos.1


Currently the cluster is configured with each node having one vote and
the quorum device having 2 votes, to allow operation in the event of
multiple node failures.

I'd like to know if there's any recommended method for changing the
quorum disk "in place", without shutting down the cluster.

The following approaches come to mind:

       1. Create a new quorum device (multipath, mkqdisk).

          Ensure that at least 2 of the 3 nodes are up.

          Change the cluster configuration to use the new path to
          the new device instead of the old device.

          Commit the change to the cluster.

       2. Create a new quorum device (multipath, mkqdisk).

          Ensure that at least 2 of the 3 nodes are up.

          Change the cluster configuration to not use any quorum
          device.

          Commit the change to the cluster.

          Change the cluster configuration to use the new quorum
          device.

          Commit the change to the cluster.

       3. Create a new quorum device (multipath, mkqdisk).

          Change the cluster configuration to use both quorum
          devices.

          Commit the change to the cluster.

             --------------------------------------------------
             Note: the 'mkqdisk' manual page (dated July 2006)
	    states:
                   using multiple different devices is currently
                   not supported
             Is that still accurate?
             --------------------------------------------------

          Change the cluster configuration to use just the
          new quorum device instead of the old device.

          Commit the change to the cluster.

Thanks for any suggestions.

Mark

With the caveat that I have not done this and make no claims to being an expert; Option 2 strikes me as the best choice.

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