Question Regarding Cluster Lock VG in RAC

[Jacob Alexander]

Hi,

I have a MC/SG RAC cluster with 3 nodes, we use cluster lock VG and cluster lock PV for the Quorum management.

In one of the nodes, alternate path for a PV is not set in the cluster lock VG. I want to add the alternate path in to this VG. But VG is not active, so I am not able to extend the path. Surprisingly, when I checked; this cluster lock vg is not active in any of the nodes.

1. Can I activate the VG and extend to the alternate path
2. Is it possible if i can export and import the vg back with both paths??

I don want to harm my running cluster.

Please advice.

Thanks, Alex

[Rita C Workman]

Well...normally you can do vg adjustements while the cluster is running. Provided the disk is already part of a vg already active in your running cluster.

But in your statement, there just seems to be a couple of 'fogs' hanging out there, so I will go to the side of caution.

There are a few things you can not adjust on a running cluster, like:
Changing timing paramater
Changing serial devices
Changing IP's
& Changing Cluster Lock Configuration

So, to reply on the side of caution, you might want to take things down. Ensure your lockdisk is see-able by all nodes properly, add in your alternate path...and restart things.

[Jacob Alexander]

Hi,

Let me clarify my qstn. Is it possible to export and reimport the cluster lock vg in one of the node, without an outage to the cluster.
Thanks, Alex

[Geoff Wild]

No - you can not change the cluster lock config:

http://docs.hp.com/en/B3936-90100/ch07s04.html#ciibdgcg


Reconfiguring a Running Cluster


You can add new nodes to the cluster configuration or delete nodes from the cluster configuration while the cluster is up and running. Note the following, however:

You cannot change the quorum server or lock disk configuration while the cluster is running.


That said, you are not changiing the lock disk, you only want to re-import the vg - in that case - you should be able to do that while the cluster is running.

Rgds...Geoff

[Kevin Wright]

Are you just looking to add in the alt path on the node that only has one path, or are you looking to add in the alternate paths to the cluster config file as well? That would be a problem, but I don't think there would be any concern activating the VG, running vgextend to the alt path, and vgchange -a n.

[Jacob Alexander]

geoff: Kevin has ponited out my requirement.
Is it possible when the cluster is up.

1. do a vgchange -a y
2. extend the alt path to the vg
3. do a vgchange -a n

Will this work when the cluster is up

Thanks., Sunil

[Geoff Wild]

Yes - that should work - as long as it isn't used by a package...

However - if the vg is cluster aware, then you need to do a vgchange -c n
first, then the vgchange -a y



Then after you are done, vgchange -c y

Rgds...Geoff