Suspending APGs or Its Members

SA z/OS also supports suspending Application Groups (APGs) and their members. But be aware that suspending only a member, leaving the containing group unsuspended, might lead to group actions for APGs of nature MOVE and SERVER, depending on what happens to this suspended member.

Taking Figure 1 for example, assume that member M1 is currently selected in the MOVE APG G and that this member is active. If it is suspended using INGSUSPD, nothing happens - M1 remains active. However, as soon as you manually stop M1, the automation manager will look for another viable member in G, find M2, and start it.

Continuing the scenario above, assume that M1 (inactive, suspended) has a base preference value of 951 and M2 (active and selected) has an adjusted preference value of 950 (base preference of 700 plus availability bonus of 225 plus sticky bonus of 25). As soon as M1 is resumed, SA z/OS performs a disruptive move by shutting down M2 and starting M1 because M1's preference value is higher than M2's.

To avoid such frequent unexpected group actions, it is recommended to suspend the whole group. Using the SCOPE parameter, you can decide whether only the group and its members or in addition all the descendants of the group and the descendants of the individual group members are suspended, too. The following figure illustrates the difference:

Figure 1. Suspend a Group and Its Members Using Scope Parameter

The parameter SCOPE=ONLY suspends the group and its members, but no dependant resources; neither dependants of the group itself (like C3) nor dependants of its members (C1 and C2). In contrast, the parameter SCOPE=ALL includes the suspension of all descendants of the group, direct and indirect descendants.

If a member is suspended directly or indirectly through the suspended group, any start or stop votes previously propagated from the group to the member and further down to all its dependants are withdrawn. For suspended members of a group of nature SERVICE or MOVE, the desired status will therefore change to the default desired status, which is usually AVAILABLE, as the member will not have a group vote propagated to it. This may result in a compound status of INHIBITED for those dependant resources that are currently not suspended. Consider using SCOPE=ALL when suspending the group in this case to avoid INHIBITED.

Taking Figure 1 for example, assume that member M2 is currently not selected in the MOVE APG G and this member is inactive. If it is suspended using INGSUSPD, the desired status for M2 will be changed to AVAILABLE, but automation will not trigger any action.

However, as soon as you resume the member using INGSUSPD, the automation manager may generate a stop vote again, changing the desired status to UNAVAILABLE if another member is still selected by the group based on current preference values.