[Ocfs2-users] Multiple clusters per node?

[Søren Kröger]

Hi Sunil

Will the mastery involve all nodes in the cluster, regardless which  
filesystem they have mounted? Or will it only involve those nodes  
which have mounted the particular filesystem?

Søren

On 28/04/2009, at 22.21, Sunil Mushran <sunil.mushran at oracle.com> wrote:

> Søren Kröger wrote:
>> I'm trying to split up our big OCFS2 filesystem into 3 separate  
>> LUN's, since there are only a limited amount of nodes which need  
>> access to the different parts of the OCFS2 filesystem.
>> One "Master" server with RW access should still be able to mount  
>> all 3 OCFS2 LUN's, all others would only mount one of the 3 LUN's  
>> in RO mode.
>
> In a distributed lock manager, no one node is the master node for
> all resources. Mastery of resources is distributed amongst all the
> nodes irrespective of the fact that a node may have mounted ro.
>
> Note that the locks on a resource are only created if a node actually
> reads that inode. So it could be that you have three nodes reading
> different directory trees that have little in common with each other.
> In that case, each node will master the resources and the only lock
> on each resource will be the local one.
>
>> What i want is:
>> - Lowering the impact, when one node crashes and causes deadlocks  
>> on the filesystem for other nodes
>
> When a node crashes, the surviving nodes will recover it. Why should
> there be any deadlocks?
>
>> - Lowering the impact, when we have to resize a OCFS2 volume
>
> ocfs2 has online file system resize. However we require a cluster
> volume manager. This should be working in SLES11 when they release
> the HA extension package. We hope to have this running with (RH)EL6.
>
>> - Lowering the mastery time
>
> Again, ro nodes have as much a say in mastery as rw.
>
>> Is there one master per filesystem or one master per cluster?
>> Would 3 separate filesystems under the same cluster be "separated"  
>> enough to achieve?