Strategies for InterChange Server Express recovery

If InterChange Server Express fails when processing events, all the events currently in the Work-in-Progress (WIP) queue must be either recovered or otherwise processed when the server reboots. Potentially, because of memory requirements, the recovery of the WIP events can slow or even halt the server reboot. The InterChange Server Express product provides two features--deferred recovery and asnynchronous recovery--for improving the time it takes the server to reboot and for making the server available for other work before all events have been recovered.

Flow control and storing business object keys as part of the WIP data assist in the efficiency of deferred recovery and asynchronous recovery. Both features reduce the amount of memory needed during an InterChange Server Express recovery, and therefore, can decrease significantly the amount of time necessary for InterChange Server Express to reboot during a recovery.

Storing business object keys as part of the WIP data means that during recovery, the business object key is retrieved without deserializing the business object, avoiding an MQ or a database round-trip. Flow control is a service that allows you to configure either system-wide or component-level queue depth parameters in to control the memory demands on InterChange Server Express. For more information about configuring flow control, see Steps for configuring system-wide flow control.

Steps for deferred recovery of collaboration events

In deferred recovery, recovery of a collaboration's WIP events is deferred until after the server has rebooted, thereby saving the memory usage associated with those events.

After the server has rebooted, you can resubmit the events manually. Note the following recommendations:

You establish deferred recovery by setting the RECOVERY_MODE property of a collaboration object.

Note:
Use of deferred recovery compromises the sequencing of events, which may cause data integrity problems. Use this feature only if sequencing is not important to you.

The RECOVERY_MODE property has two settings, which do the following when a server failure and reboot occurs:

The default setting is Always.

Note:
Changing the collaboration recovery mode value from Deferred to Always does not recover deferred events, nor does it change existing deferred events to the Working state. Events in the deferred recovery state remain deferred until you manually resubmit them.
Perform the following steps to set the collaboration Recovery mode value:
  1. From System Manager, right-click a collaboration object and click Properties. The Properties dialog box appears (see Figure 60).
  2. In the Collaboration Properties dialog box, click the Collaboration General Properties tab. The following dialog box opens:

    Figure 60. Properties dialog box, Collaboration General Properties tab


  3. In the Recovery Mode list, select one of the following:

Asynchronous recovery

InterChange Server Express does not wait for collaborations and connectors to recover before it completes the boot process; collaborations and connectors are allowed to recover asynchronously after InterChange Server Express has booted. This makes it possible to use troubleshooting tools -- such as System Monitor, Failed Event Manager, and Flow Manager -- when the connectors and collaborations are recovering.

Copyright IBM Corp. 2004