Saturday, February 16, 2008

HA failover scenarios1

Graceful For graceful failover, you can run “smitty clstop” then select graceful option. This will not change anything except stopping the cluster on that node.Note: If you stop the cluster, check the status using lssrc –g cluster, sometimes clstrmgrES daemon will take long time to stop, DO NOT KILL THIS DAEMON.It will stop automatically after a while.You can do this on both the nodes2. TakeoverFor takeover, run “smitty clstop” with takeover option, this will stop the cluster on that node and the standby node will take over the pakageYou can do this on both the nodes3. Soft Pakckage Failover Run smitty cm_hacmp_resource_group_and_application_management_menu >>>Move a Resource Group to Another Node >>>>select the package name and node name >>>enterThis will move the package from that node to the node that you have selected in the above menu. This method will give lot of troubles in HA 4.5 whereas it runs good on HA 5.2 unless we have any apps startup issues.You can do this on both the nodes│ 4. Failover Network Adapter(s):For this type of testing , run “ifconfig enx down” , then package IP will failover to primary adapter. You can not even see any outage or anything.We can manually (ifconfig enx up) bring it back to original adapter , but better to reboot the server to bring the package back to the original node5. Hardware Failure (crash):This is a standard type of testing; run the command “reboot –q” then the node will godown without stopping any apps and come up immediately. The package will failover to the standby node with in 2 min os downtime (Even tough HA failover is fast, some apps will take long time to start

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