topic Re: clustering doubt in Operating System - HP-UX

clustering doubt

kamal_9 — Thu, 08 Jul 2004 09:57:25 GMT

In a two node cluster if the cluster lock is currenrtly locked in systemA and if all of a sudden the power in systemA goes off.then how the systemB will get the cluster lock to reform the cluster.

Re: clustering doubt

Geoff Wild — Thu, 08 Jul 2004 10:00:26 GMT

Niether node will lock the cluster lock disk unless it has lost communication with the other node - when that happens, 1 node will get it - the other will TOC.

Rgds...Geoff

Re: clustering doubt

Sridhar Bhaskarla — Thu, 08 Jul 2004 10:00:56 GMT

Hi Kamal,

When the cluster is running, cluster lock won't get locked with any of the systems. It's attained only if one system cannot see the other system. If the systemA goes off, then systemB will automatically succeed in obtaining the cluster lock as there is no competition to it. Otherwise whichever the system gets the cluster lock first would take over.

-Sri

Re: clustering doubt

Manish Srivastava — Thu, 08 Jul 2004 10:01:12 GMT

Hi,

I do not know what is a cluster lock? is it the quorum disk you are talking about?

manish

Re: clustering doubt

Gary L. Paveza, Jr. — Fri, 09 Jul 2004 12:26:42 GMT

The cluster lock should be on a drive which is shared between all nodes in the cluster. One node will always be able to get the lock.

Re: clustering doubt

Karthik S S — Fri, 09 Jul 2004 12:51:31 GMT

When SystemA - Power fails, then SystemB wont able to receive the heartbeat signals from SysA. Thus, it will succeed in obtaining the clusterlock/quorumdisk which is on a shared disk array b/w SysA and SysB.

-Karthik S S

(Hi there ITRC :-), after a long gap I am back)

Re: clustering doubt

Sundar_7 — Fri, 09 Jul 2004 12:57:42 GMT

It is not like a system keeps a cluster lock disk locked all the time - it is just used for split of a second when the split brain situation occurs. So if both systemA and systemB are currently part of the cluster, none of them are holding the cluster lock - both the machines are free to lock the disk (for sometime) if the other nodes goes down or there is any communication failure.

In this case, whichever node managed to lock the disk first will form the cluster, the other node can join the cluster if it managed to recover from the failure. If not, the cluster safety timer times out in the other node and it is TOCed.