Central storage dynamic storage reconfiguration examples

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Figure 1 shows an example of central storage with dynamic storage reconfiguration capability. This figure shows LP-A, LP-B, and LP-C.

central storage layout — Figure 1. Central storage layout

To reconfigure central storage, deactivate LP-B to free up storage directly above LP-A. Figure 2 shows how you may reconfigure central storage in this case.

reconfigured central storage layout — Figure 2. Reconfigured central storage layout

Figure 3 is another example of dynamic reconfiguration of central storage. For this example, assume the amount of customer storage is 16384 (16T). The amount of addressable central storage used by hardware system area (HSA) is 74 GB in this example. The storage granularity is 1 GB. This leaves 16310 GB of central storage addressability to be allocated to LPs.

LP-A and LP-B are defined with an initial amount of 14 GB each of central storage, a reserved amount of 2 GB, and system determined central storage origins. LP-A and LP-B are activated and IPLed. At the completion of IPL, LP-A has its reserved central storage configured online by entering CF STOR(E=1),ONLINE from the z/OS® software console for LP-A. Figure 3 shows the resulting storage layout following these actions.

Figure 3. Initial central storage layout

At a later time, the reserved storage from LP-A can be reconfigured to LP-B.

Note: Both LPs should specify an RSU value of at least 2 (2048/1024) for reconfigurations of storage to work.

From the z/OS software console for LP-A, enter CF STOR(E=1),OFFLINE. Next, from the z/OS software console for LP-B, enter CF STOR(E=1),ONLINE. Figure 4 shows the resulting storage layout following these actions. The reserved storage is fully reconfigured without an outage to either LP. Also, the procedure can be reversed without an outage as well.

Figure 4. Central storage layout following reconfiguration