It is a good idea to install agents on any backup server where ILMT is also installed on the primary server in order to monitor the processor core capacity required for licensing terms. We all know that managing data center server software licenses can be challenging. Dealing with the licensing terms and conditions for backup servers is one of those challenges. These instances can then be excluded from PVU calculation if a license is not required (typically warm/cold backups, but license requirements can vary by product).
Backup or Standby Systems
Backup licensing enables a business to continue operating in case of an emergency. Whenever backup and recovery services are involved, this is referred to as backup use or disaster recovery, or referred to as BRS.
IBM defines three kinds of backup scenarios for programs running on backup machines: cold, warm, and hot.
Hot Backup Server
In this case, the standby server is one that receives regular updates from the production server and is always ready (hot standby) to take over immediately in case the production server fails. Both primary (production) and secondary (hot backup) systems can run at the same time, in which case data is mirrored to the secondary system in real time. You will need a license for both the production server and the hot backup server in most cases.
Warm Backup Server
In either situation, the server is running, but is idling and not doing anything, or it is turned on periodically to receive updates from the server being backed up. A warm server is often used for “replication” and “mirroring.” It is possible for the warm (mirrored) server not to have the exact same data as the primary (production) server at times. It depends on the vendor, application and licensing agreement whether you need a license for the warm backup server.
Cold Backup Server
In this case, the server is turned off until a disaster strikes and you need to enter disaster recovery (DR). Cold backup servers usually do not require separate licenses.