3 Node Cluster

[Darren Murray]

We are running a 3 node cluster.

I know with a 2 node cluster you need a cluster lock disk.

Is it a good idea to have one in 3 node cluster?

We are also using a fc-60 and 3 sc-10's is there anyway of making a Raid 0 Lun for the cluster lock disk and I dont want to waste the slot and disk space

Darren

[Sanjay_6]

Hi Darren,

I believe HP recommends that If your no of nodes are less than or equal to 4 you should use a lock disk. You may face a tie breaking situation even with the 3 node configuration. So it would be good if you configure the lock disk.

Also you can use a RAID 0 configuration for your lock disk, I think.

Hope this helps.

thanks

[Sridhar Bhaskarla]

While the lock disk is a must for a two node cluster, the probability of 'tie break' in case of three node cluster is unlikely and it becomes minimum as you go up. The idea to recommend a lock disk even for a three node cluster is that it will become a two node cluster if one node goes down which is dangerous until you get the third node up again.

So, it is not a must to have a cluster lock disk. But it is upto you to decide based on the criticality VS your resources.

-sri

[melvyn burnard · Accepted solution]

The FC60 is supported as a cluster lock disk only on SG A.11.09 with PHSS_23511 (or later) installed or with SG A.11.12 or later. A patch will be required for SG A.10.12 for the FC60 to be supported as a cluster lock disk on
HP-UX 10.20.

It is not a MUST HAVE for a cluster lock disc in a 3 node cluster, but it is a good idea as previously mentioned due to the possibility of problems caused if one of the 3 nodes is taken out due to problems, or shutdown for maintenance, and then you have a another problem on one of the two remaining node.
The option is yours.