If your installation has multiple processors, you must decide how many processors to process in the same old/new set of history files. You may decide to have a separate history file for each processor or a single history file for all your processors that share a common IBM® customer number. Once you decide, the same processors must always be associated with the same set of history files. There are three rules you must follow to determine which processors can/must be processed in the same history file:

1. All the OS/390® and z/OS® guests or LPARs on the same processor must use the same set of history files.
2. All the processors in a parallel sysplex must use the same set of history files.
3. All the processors in the same history file must share a common IBM customer number.

There are several advantages to associating as many processors as possible with a single history file. They are:

1. A single execution of IFAURP can process the records from all the processors associated with the history file.
2. A single execution of IFAURP can produce all the reports for all the processors associated with the history file.
3. It simplifies defining existing coupling capable processors as part of a new parallel sysplex.
4. The reporting dates, measurement period, and billing periods for all processors and sysplexes in the same history file, are printed on a single Time Period Report for each vendor's products.
5. The relative position of the months in the Software Usage Report is the same for all processors sharing a common history file, regardless of the earliest START data on each of the processors.