In Figure 1, system SYS1 fails. System logger recovery processing for SYS1 consists of moving all the coupling facility resident log data for the system to DASD log data sets. Because SYS1 is connected to log streams on coupling facility structure A, it needs a peer connector with a connection to structure A to perform recovery. SYS2 can perform recovery for SYS1 because it has a system logger application connected to a log stream that maps to coupling facility structure A. SYS3 is not a peer connector for SYS1 and cannot perform recovery because it does not have a connection to coupling facility structure A.

Figure 1. Example: Recovery for a Failing System - All Data Recovered

In Figure 2, system SYS1 also fails. SYS1 has connections to coupling facilities structures A and B and so needs peer connectors to both structures to recover all its coupling facility resident log data. SYS2 can perform recovery for SYS1 log data on coupling facility structure B, but there is no peer connector to perform recovery for SYS1's log data on coupling facility structure A.

Recovery for SYS1's coupling facility structure A log data is delayed until either SYS1 re-IPLs or another system connects to a log stream on coupling facility structure A.

Figure 2. Example: Recovery for a Failing System - Recovery Delayed for Some Data