Switchover of the Redundant Batch subsystem
Switchovers occur either manually, initiated from DeltaV Diagnostics; or, systematically from an unexpected shutdown of the Batch Executive (or Campaign Manager, if enabled); or, from the loss of the computer on which the Batch subsystem is running. The switchover is normally not noticed by the operator (exclusive of any alarms or alerts or the hold propagation setting), however the clients might become temporarily slower to respond or the latest commands and prompt acknowledgements (if issued during a switchover) might be reissued.
Do not force a switchover by shutting down the active node using either the Start menu or the power button as the Batch Manager is not always shut down first and the standby will not always have the correct information. This is due to the method the operating system uses to perform a shutdown and is not the same as the loss of power to the system.
If the Batch Executive and Campaign Manager are both enabled on the redundant pair and a switchover occurs for either the Batch Executive or the Campaign Manager, then both the Batch Executive and Campaign Manager will switchover at the same time.
When a switchover occurs (the standby is available, that is, PAVAIL = TRUE), the new active:
processes the queued runtime updates from the former active partner and flushes the transmit queue
starts monitoring the batch directories and registry for persistence data changes
starts monitoring the partner state
sends alerts of the switch to all registered applications
activates the batch runners, putting them into the state they were in before the switchover
The exact state of the batches can be affected by the Batch Executive if the configuration setting, Hold any running batches on switchover, is enabled.
The switchover event is listed with the name of the newly active node (the node that was switched to). The node name is listed in the User column of the event record.
After a switchover, any unacknowledged requests are re-sent. The request is not incremented (therefore no need to release it more than once). In the case of resource requests, if the resource is already acquired by the requesting phase (acquire occurred at the point of switchover but the acknowledgement was not received in time), a message is sent stating that the phase already owns the resource.
During a switchover, all pending Active Step Changes (ASC_PENDING) are cancelled. Active Step Changes that are ASC_WORKING maintain that status in a switchover and will continue to be processed.
If a batch is in Manual mode after a switchover, you can put it back into Auto mode by clicking the Auto button on the batch toolbar.
If a switchover is executed while the standby is not fully operational (PAVAIL is FALSE) then the resulting batch behavior is the same as if the standby was not configured. Switchover, in this case of PAVAIL is FALSE, is only possible if the active ceases to exist (due to power failure on the active, loss of both ACN connections, and so on). Redundancy could be temporarily unavailable while the initial updates are in progress.
If a switchover occurs while the initial updates are in progress, batch applications that are already started as a part of the initial updates are shut down. All batch applications will have to be restarted manually. This is equivalent to a cold restart of a simplex Batch Executive.