System failure

When the IMS system fails during a CPI Communications driven LU 6.2 conversation, IMS determines whether to resolve in-doubts for IMS-protected resources. Examples of IMS-protected resources are IMS DB databases, Db2 for z/OS® databases, and IMS TM messages.

For standard and modified standard DL/I application programs, if the IMS system fails before the transaction completes phase one of the two-phase commit sync-point protocol, IMS backs out changed data during IMS restart. This backout includes all discardable transactions that were processing at the time of the system failure. IMS requeues non-discardable transactions so they can be processed.

If the transaction completes phase one of the two-phase commit, IMS resolves in-doubts during IMS restart. If only IMS resources are affected, IMS commits changes. If Db2 for z/OS resources are affected, IMS tells Db2 for z/OS to commit or abort the changed data, as appropriate.