cluster lock disk configuration in HPUX MCSG three node cluster

[sbb]

Hi,
I want to know how we can configure cluster lock in three node cluster.
My cluter configuration will be like...

NodeA->Running SAP as a application
NodeB->Running another SAP as a application
NodeC-> will be standby and will be failover node for NodeA and NodeB.

NodeA and NodeB will not be fail over to each other.
storage will be SAN storage.
there is no shared VG's between NodeA and NodeB.
All VG's of NodeA and NodeB will be exported to NodeC only.

So in this situation how we can configure cluster lock disk/VG. or Is it really neede to have cluster lock.

[Victor Fridyev]

Hi,
Cluster lock is obligatory for 2-node cluster only. If a cluster has more than 2 nodes, lock disk is optional.
HTH

[Ivan Krastev]

In your scenario, if one of the nodes fail or it is removed for maintenance - it will be better to have a lock disk or quorum server.

See more about arbitration in SG clusters - http://docs.hp.com/en/B3936-90078/ch01.html

regards,
ivan

[melvyn burnard]

To have a cluster lock disk, ALL of teh cluster nodes MUST share access to this disk.
if you cannot provide this, you cannot use a cluster lock disk.
For a 3 node cluster, a lock disk is optional, as is a quorum server, and I would recommend you set up a quorum server for this cluster.

[Dirk Timmermann]

Isn't it possible to use FIRST_CLUSTER_LOCK_PV for lock disk between NodeA and NodeC and SECOND_CLUSTER_LOCK_PV between NodeB and NodeC

[melvyn burnard]

Dirk
Absolutely not!
ALL nodes MUST have access to the cluster lock disk

[Mridul Shrivastava]

As others already mentioned all nodes must have access to the cluster lock disk. And it will be required if one node is down or taken out for maintenace for a longer period... Since in that case it will be two node cluster and if there is a hearbeat miss etc then cluster lock disk would be used...

This is the reason it is optional for 3 or more node cluster setups.