Loss of connectivity to a coupling facility can occur because of a failure of the coupling facility attachment or because of certain types of failures of the coupling facility itself. MVS™ provides the capability to initiate a rebuild of one or more structures in the coupling facility to which connectivity has been lost, using the CFRM policy and optionally, the SFM policy.

For each structure defined in the CFRM policy, you can specify a value that MVS will use to determine whether to initiate a structure rebuild when a loss of connectivity occurs. When an active SFM policy is in effect in the sysplex and a coupling facility loss of connectivity occurs, MVS uses the system weights defined in the SFM policy in conjunction with the REBUILDPERCENT value defined in the CFRM policy to determine whether to initiate a structure rebuild. Using the SFM policy system weights, MVS calculates the weighted percentage of lost connectivity and compares the result with the user-specified REBUILDPERCENT value. If the calculated percentage value is greater than or equal to that specified by REBUILDPERCENT, MVS will initiate the structure rebuild.

With OS/390® R3 and higher, with OW30814 installed, MVS will initiate a rebuild when loss of connectivity to a structure occurs and there is no active SFM policy in the sysplex.

See Specifying a rebuild threshold for information about MVS-initiated structure rebuild.