How TOM communicates with other TOM PASs in a TOMPLEX

This data is maintained in the TOM registry data set, which is specified by the REGISTRY_DSN parameter in BBPARM member MAMPLXxx. There is one registry data set per TOMPLEX. For more information about the registry, see Overview of the registry.

The first TOM PAS to complete initialization in a TOMPLEX becomes the owning PAS of the registry (owner). Other TOM PASs that join the TOMPLEX are considered remote user PASs and make registry services requests through the owner by using XCF communications facilities. If the owner PAS terminates, one of the remote PASs automatically becomes the owner PAS. This process is referred to as failover recovery.

If this ownership-transfer (failover recovery) process takes more than one minute, a warning message is issued every five seconds indicating that a failed registry request is being retried. The warning messages continue until the TOM PAS is stopped or the reason for the delay in failover recovery is corrected. Delays could be caused by XCF errors, data set allocation reserves, or other miscellaneous system problems.

• Scenario 1: One TOM PAS starts before other TOM PASs
• Scenario 2: One TOM PAS loses contact with other TOM PASs in a TOMPLEX
• Objects with a status of BLOCKED