What causes a SQL Cluster to Failover? -- sql server clustering

sql server clustering : What causes a SQL Cluster to Failover?

Mike Epprecht (SQL MVP)
6/28/2005 12:00:00 AM

Hi

When the connectivity is lost at both IP and SAN level to the other node, a
failover occurs.

If the server that is running the instance takes too long to respond to a is
alive.

Clustering does not care about a bad application that is bleeding RAM, as
long as the server responds to is alives, it stays in the cluster.

If the application is cluster compliant, then clustering services can manage
it, otherwise clustering just cares that the server is up. Clustering
compliance involves WMI and other API requirements from the application.
MSDN has the information on it.

SQL Server is cluster compliant.

Regards
--------------------------------
Mike Epprecht, Microsoft SQL Server MVP
Zurich, Switzerland

IM: mike@epprecht.net

MVP Program: http://www.microsoft.com/mvp

Blog: http://www.msmvps.com/epprecht/

[quoted text, click to view]

tjhazel
6/28/2005 8:34:05 AM

What causes SQL Server to fail from the active node other than the heartbeat
flat-lining? I have the cluster installed and tested the heartbeat by
unplugging the active machine. Failover works great.

My question is what else can cause the failover? Lets say we have a memory
leak. Is there a point when the heartbeat is still fine, but the memory is
slowly being consumed. Is there a threshold that causes a failover?

What about an application that is hung and consuming excessive cpu cycles.
Assuming the heartbeat is still alive, is there a point when the active node
will fail over?

Is there a good white paper or kb article that can help shed some light on
this question?

Thanks,

Charles Tolento
6/29/2005 6:59:14 AM

TJHazel

Here is a link to some SQL Cluster Failover tests.

http://www.sql-server-performance.com/sqlserver2000_clustering_install_part4.asp

Also if you are able to unplug the heartbeat from the current active node
and failover occurrs you need to setup your public nic for "All
communications". This will allow the public nic to handel the hearbeat if
the private network fails.

Check out KB 258750 for heartbeat configuration.

Regards

CT

[quoted text, click to view]

Got something to say? Click here to post a reply to this thread.

Don't see what you're looking for? Try a search.

View other messages about sql server clustering

View Other Months
June 2003
July 2003
August 2003
September 2003
October 2003
November 2003
December 2003
January 2004
February 2004
March 2004
April 2004
May 2004
June 2004
July 2004
August 2004
September 2004
October 2004
November 2004
December 2004
January 2005
February 2005
March 2005
April 2005
May 2005
June 2005
July 2005
August 2005
September 2005
October 2005
November 2005
December 2005
January 2006
February 2006
March 2006
April 2006
May 2006
June 2006
July 2006
August 2006
September 2006
October 2006
November 2006
December 2006
January 2007
February 2007
March 2007
April 2007
May 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007

home · blog · groups

Questions? Comments? Contact the dn