2 Different Clusters, Duplicate SCS Nodenames?

[Michael Hackelton]

Hi.

I currently have an old OpenVMS 6.2 cluster and am building a new, completely separate cluster using OpenVMS 8.3, to replace it with. Both clusters reside on the same network, but of course have different IP/DNS information.

We are running DECnet on the old 6.2 cluster, but not on the new 8.3 cluster. Multinet is being used for TCPIP on both clusters.

I've done some testing and successfully renamed a cluster node (8.3) using information I found in a previous forum posting.

My question is: can I rename my (SCS) nodes in the new cluster to be the same as the ones in the old cluster?

I know that the internal cluster nodenames are not dependent on the TCPIP names. I want to make sure that renaming the new nodes to match the old ones won't in some way effect my old cluster nodes. I can't see where they would since I am not running DECnet on the new cluster.

Can someone verify this fact for me? Thanks very much. I've done some searches through the forums and read through the HP OpenVMS FAQ, but haven't discovered the answer to my question.

-Mike

[Robert Gezelter · Accepted solution]

Mike,

If the two clusters see each other on the network, this could cause a problem (see Hoff's comment in another thread on renumbering issues).

However, setting the cluster group number (see the HELP text in SYSMAN under SET CLUSTER_AUTHORIZATION/GROUP_NUMBER) will ensure that the clusters do not get confused.

I have had problems at a few clients over the years when two Local Area VMSclusters existed on disjoint LANs. A small (unannounced) "improvement" in network topology caused significant problems. Needless to say, Cluster Group Numbers and passwords prevent things that should not happen from becomming serious problems.

- Bob Gezelter, http://www.rlgsc.com

[Michael Hackelton]

So if I'm understanding you correctly, I make sure my cluster numbers are different, which they are, and I should be okay to use the same nodenames in both clusters.

Still looking for the posting you mentioned that Hoff made. Also have to read up on the SYSMAN help item you mentioned.

Thanks very much!!

-Mike

[Hoff]

>>>
My question is: can I rename my (SCS) nodes in the new cluster to be the same as the ones in the old cluster?
<<<

IP and DECnet are not related to SCS in any direct fashion, and SCS does not (presently) operate over nor require IP, nor over DECnet. IP and DECnet are unrelated to clustering.

(Ok, so yes, there are a few overlaps. And there are cases where DECnet wants to use the SCS cluster address for its own purposes. And where the cluster addresses can require specific product startup ordering in the system startup. And yes, having IP and/or DECnet around can be really handy. But neither IP nor DECnet is required. But I digress. :-) )

For this case? Change the SCS group number. Change the password while you're at it. This cluster group number value is used to build the Ethernet multicast address used for SCS communications within the cluster, and this mechanism is the underpinnings of cluster communications, command and control. With a different group number, the two clusters will *not* see each other.

I've updated http://64.223.189.234/node/169 with this detail.

Stephen Hoffman
HoffmanLabs

[Hoff]

>>>
Still looking for the posting you mentioned that Hoff made.
<<<

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1112130

[Robert Gezelter]

Mike,

I see Hoff beat me to it. He has just posted the link that I was about to post.

Hoff: Thank you! I was on a client conference call.

- Bob Gezelter, http://www.rlgsc.com

[Michael Hackelton]

Thanks for the great support. Your comments solved my problems. I've now got 2 physically separate clusters, both using the same node names.

-Mike