Saturday, February 16, 2008

HACMP topology

Hacmp can be configured in 3 ways.1. Rotating2. Cascading3. Mutual FailoverThe cascading and rotating resource groups are the “classic”, pre-HA 5.1 types. The new “custom” type of resource group has been introduced in HA 5.1 onwards.Cascading resource group:Upon node failure, a cascading resource group falls over to the available node with the next priority in the node priority list.Upon node reintegration into the cluster, a cascading resource group falls back to its home node by default.Cascading without fallback Thisoption, this means whenever a primary node fails, the package will failover to the next available node in the list and when the primary node comes online then the package will not fallback automatically. We need to move package to its home node at a convenient time.Rotating resource group:This is almost similar to Cascading without fallback, whenever package failover to the standby nodes it will never fallback to the primary node automatically, we need to move it manually at our convenience.Mutual takeover:Mutual takeover option, which means both the nodes in this type are active-active mode. Whenever fail over happens the package on the failed node will move to the other active node and will run with already existing package. Once the failed node comes online we can move the package manually to that node.

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