The Server Units offer improved high availability for CPUs as well as the ability to temporarily attach preinstalled CPUs that expand the computing capacity of the server slightly beyond its nominal value.
When a BS2000 CPU fails, an existing spare CPU is automatically attached. The nominal performance of the Server Unit is thus guaranteed.
On an SU/390 one spare CPU is available for this purpose.
On an SU x86 a CPU not previously used by BS2000 is employed when system startup takes place following a CPU failure.
In addition to the spare CPU, if necessary, additional Server Unit power can be temporarily installed beyond the nominal number of multiprocessors (MP level) on the Server Unit in the form of extra CPUs whose duration of usage is specified in a contract. The extra CPUs are attached and detached by systems support using extended CPU reconfiguration commands. The usage intervals are recorded in BS2000 in a separate log file and also appear as messages sent to remote service.
See the “VM2000” manual [60] for more information on using spare/extra CPUs in VM2000.