If a ring rebuild seems to hang, quiesce one of the systems until the XCF failure detection interval is reached. The system issues message IXC402D to indicate that communications with that system has been lost. Restart the system and see if the ring successfully rebuilds. If the ring does not completely rebuild after one or two attempts, the system(s) that have not rejoined the complex will not do so. Partition the system(s) from the sysplex (using the VARY XCF,system,OFF command) and re-IPL. If possible, obtain a standalone dump of the failing system(s) and contact IBM® Service.