Can Service Guard run on a Single node ?

[Sushil Singh_1]

Hi All,
Due to unforseen, situation has arise where we have to spilt our cluster to run 2 different environment. The problem and the question is "Can Service Guard run on Sinlge Server ?" If yes, does any one know where I can find the information or dcoumentation.

Thanks
Sushil Singh

[James R. Ferguson]

Hi:

Certainly a 2-node cluster can be reduced (by intention or by failure) to a 1-node environment. However, there would be little sense to running MC/ServiceGurad on a single node as the normal environment.

Regards!

...JRF...

[Victor_5]

MCSG is trying to avoid SPOF Single Point of Failer, for running on a single server, it is does not make sense.
What if power failer or network failer, so the answer is no.

[Helen French]

Hi Sushil:

It doesn't make any sense or use when a high availability cluster software running on a single node. For the specific question, MC/SG will work on a single node during a failover or manual testing time.

If you are going to use single node, then there is no point in keeping this cluster software running on it.

HTH,
Shiju

[Sushil Singh_1]

Thanks for the reply Guys,
It really doesn't make sense to run service guard on a Single server. But I was wondering if I can expliot the feature that service guard has. I am not looking for any failover feature. I need to use the monitoring feature. Like software interrupts, hardware failure, monitoring alarms for these failure.

I am able to implement this on a IBM Single node using HACMP. So I was wondering if I can do the same for HP too using service guard.

But thanks guys.

[hpuxrox]

Sushil,

It sure can. Some clients order it just for its lan card failover ability.

Regards,

Yates

[melvyn burnard]

This question has been asked and answered in the forums before.
The straight and simple answer is YES, you can run a sungle node cluster.
many people do this for testing, using hte lan failover, or for teaching/learning facilities.
Most importantly it is supported.

HTH

[Roger Baptiste]

hi,

Yes, it can run on one node. There is no special instructions for this. You can follow the same process as for a multinode cluster.

HTH
raj

[Mladen Despic]

See p. 187 of the following document:

http://docs.hp.com/hpux/pdf/B3936-90053.pdf

[Stephen Doud]

Hello Sushil,

To start a one-node cluster, use this command syntax:

# cmruncl -n

ServiceGuard will warn that it does not know the state of the other node in the cluster and requests permission to proceed.

Whether the alternate node is down for repair, or disconnected from the cluster, the above command will allow a one-node cluster to be formed.

Be advised that even though AUTOSTART_CMCLD=1 might be configured in /etc/rc.config.d/cmcluster, the node will NOT automatically form a one-node cluster because the partner node is not also attempting to form a cluster or already running ServiceGuard.

This can be resolved by dissolving the current cluster (cmdeleteconf) and creating a new one-node cluster:
# cmquerycl -C -n

Edit the file to increase NODE_TIMEOUT and MAX_CONFIGURED_PACKAGES and then cmapplyconf that file:
# cmapplyconf -C -P ...

-s.

[Martin Johnson]

Yes, you can run a single node cluster.

Besides testing, we have the cluster automatically restart the critical application on the node if it should stop. We limit it to 10 retries in case there is a problem that prevents the application from restarting. This provides high availability for the application.