[Linux-cluster] SOS - Can we use mixed GFS cluster?

[Bob Peterson]

On Fri, 2008-01-25 at 12:57 -0800, Lee X wrote:
> Hi,
> 
> I would appreciate it if some one could tell me if
> it's okay to use a mixed GFS cluster.
> 
> Say there are three nodes in a GFS cluster.  One use
> GFS-modules-6.0.2-25 and other other two use
> GFS-modules-6.0.2.36-1.  If not, why?  If yes, are
> there any potential problems?
> 
> Regards,
> BJ
> --

Hi BJ,

The ondisk format of GFS has not changed, so you should be okay
mixing different versions of GFS.  Having said that, you should
be more concerned with the rest of the cluster infrastructure.

There was a cman protocol change between RHEL4U1 and RHEL4U2 
(and similar releases for other distros) that makes it impossible
to mix those within a cluster.  However, versions after that are
compatible between major releases.  So in theory, the cluster
infrastructure in RHEL4.2 will play nice with RHEL4.3, RHEL4.4,
RHEL4.5, Centos 4.4, Centos4.5, and so on.

However, you still cannot have RHEL4.x nodes and RHEL5.x nodes
in the same cluster.

The ondisk format for GFS has not changed between releases,
so in theory you could even take a SAN that was formatted and used by
a RHEL4.x cluster and move the storage over to a RHEL5.x cluster,
or upgrade the whole cluster from RHEL4 to RHEL5.

Regards,

Bob Peterson
Red Hat GFS