Partitions are by default highly available. A partition will only
be hosted on a single cluster member at a time. They are made highly
available using the high availability (HA) manager component. If a
cluster member fails either because of a Java Virtual
Machine (JVM) shutdown, a JVM panic or the box hosting the cluster
member fails/gets powered down then the HA manager moves all partitions
which were running on the failed cluster members to the surviving
cluster members.
The following are the state transitions a partition will encounter
as member of a HA group.
- IDLE
- Partition is currently deactivated and waiting for an activation
command, a partition is in this state at the Bean start during server
startup after the createPartitionDefinition method until the PartitionLoadEvent
API is called by the HA manager coordinator.
- ACTIVATING
- The HA manager is attempting to activate the partition but has
not been acknowledged yet, this is in effect during the PSSB PartitionLoadEvent
method execution.
- ACTIVATED
- This means the partition currently activate and working. The PartitionLoadEvent
event has completed. This state implies that the HA manager has picked
a target application server for this partition, it is active and ready
to process methods, and the workload management layer has enabled
for client to route requests to the particular application server
associated with the specific partition.
- DISABLED
- This means the partition cannot become an active member while
still part of the group. This is a failure state.
- DEACTIVATING
- The partition received a deactivate signal and is still deactivating.
This occurs while the PartitionUnloadEvent method executes in the
partitioned stateless session bean (PSSB) for this partition. The
partition then returns to IDLE and the HA manager signals the activate
coordinator managing that group and provides a copy of the current
local state.
