During the application testing phase of a virtual switch, apply processes are ended and replicated transactions wait to be applied. Recovery actions initiated by replication processes and target journal inspection during virtual switch testing use a configured delay time with a default value of 5 minutes. Optionally, you can change the delay time.
The source capture delay value needs to be an acceptable balance between increased risk and resource usage for the amount of time that you expect to remain in the application testing phase of a virtual switch. During virtual switch testing, your environment is already exposed because transactions accumulate on the target node and are not applied until after the testing phase of the switch completes. The volume of transactions, recovery actions, and how frequently recovery actions capture source information can affect apply process backlogs and resource usage. All transactions that have accumulated for apply processes during testing, including those for new recoveries, are applied during the recovery phase of a virtual switch. The virtual switch recovery phase must complete before a planned or unplanned switch of the application group can be performed.
During virtual switch testing:
No delay allows the information needed for recoveries to be immediately captured and sent to the target. This represents the least risk in the event of the loss of the source node. However, frequent access of source objects may interfere with applications and increase communication usage, and the increased transactions may quickly increase apply process backlogs.
A delay time may reduce the number of captures needed for an object or file, reduce communications usage, and place fewer recovery-related transactions into the queues for apply processing. However, the objects and records identified by new recoveries created during virtual switch testing are not synchronized, and their source information will not be sent to the target node until the delay time is reached.
The value Delay Until Recovery (*VRTSWTRCY) delays all source captures for target journal inspection recovery actions created during the application testing phase of a virtual switch until the virtual switch recovery phase starts. If your environment has workload or storage constraints, this may be more efficient. The source information needed to synchronize affected target node files and objects is not captured and sent to the target node at or near the time the errors occurred, which is an exposure in the event of the loss of the source node. Also, the virtual switch recovery phase may be slower because it includes all delayed capture operations as well as applying transactions that accumulated while testing.
To change the source capture delay used during the application testing phase of a virtual switch, do the following:
From the command line type SETMMXPCY and press F4 (Prompt).
Verify that the value specified for Data group definition is *INST.
Press Enter to see all the policies and their current values.
For the Virtual switch testing prompt under Source capture delay (min.), specify one of the following:
Specify the number of minutes to delay source captures.
Specify *NONE to have recovery captures performed immediately.
Specify *VRTSWTRCY to delay the source capture until the application testing phase of the virtual switch is complete and virtual switch recovery starts.
To accept the changes, press Enter.
Changes become effective automatically as the replication manager checks for recoveries to process.