MASTER

   .-MASTER---.   
>>-+----------+------------------------------------------------><
   '-NOMASTER-'   

One member of a sysplex is selected by RMF to gather Monitor III data. This is called sysplex master gathering and has been implemented to reduce workload on non-master members and to reduce the amount of data in SSHs and SMF records. The RMF™ Master Gatherer system is determined by the RMF Sysplex Data Server automatically according to the following set of rules:

1. Monitor III gatherer active
2. highest z/OS release
3. Sysplex Data Server running with SMF buffer (SMFBUF option)
4. MASTER option specified

You can use the MASTER parmlib option to refine the determination, which of the systems in a sysplex becomes the RMF Master Gatherer system. If the MASTER option is specified for a certain system, this system is one candidate for the MASTER status. If NOMASTER is set, it will not be a MASTER candidate if there are other eligible systems having the MASTER option set. Thus you can use a combination of MASTER/NOMASTER options to select the RMF Master Gatherer system, if there are several systems, that fulfil the priorities 1 through 3 rules simultaneously.

Beyond using the MASTER option, the Monitor III Master Gatherer status of a system can be changed dynamically by means of MODIFY commands as described in Modifying RMF session options.