RMF

The Resource Management Facility (RMF™) collects system-wide data that describes the processor activity (WAIT time), I/O activity (channel and device usage), main storage activity (demand and swap paging statistics) and system resources manager (SRM) activity (workload).

RMF Version 4 is a centralized measurement tool that monitors system activity to collect performance and capacity planning data. The analysis of RMF reports provides the basis for tuning the system to user requirements. They can also track resource usage.

RMF Version 4 measures these activities:

• Processor usage
• Address space usage
• Channel activity:
  • Request rate and service time per physical channel
  • Logical-to-physical channel relationships
  • Logical channel queue depths and reasons for queuing.
• Device activity and contention for the following devices:
  • Unit record
  • Graphics
  • Direct access storage
  • Communication equipment
  • Magnetic tapes
  • Character readers.
• Detailed system paging
• Detailed system workload
• Page and swap data set
• Enqueue.

RMF Version 4 lets the z/OS user:

• Evaluate system responsiveness:
  • Identify bottlenecks
  • The detailed paging report associated with the page and swap data set activity can give a good picture of the behavior of a virtual storage environment.
• Check the effects of tuning:
  • Results can be observed dynamically on a screen or by postprocessing facilities.
• Perform capacity planning evaluation:
  • The workload activity reports include the interval service broken down by key elements such as processor, input/output, and main storage service.
  • Analysis of the resource monitor output (for example, system contention indicators, swap-out broken down by category, average ready users per domain) helps in understanding user environments and forecasting trends.
  • The postprocessing capabilities make the analysis of peak load periods and trend analysis easier.
• Manage the larger workloads and increased resources that z/OS® can support.
• Identify and measure the usage of online channel paths.
• Optimize the usefulness of expanded storage capability.

RMF measures and reports system activity and, in most cases, uses a sampling technique to collect data. Reporting can be done with one of three monitors:

1. Monitor I measures and reports the use of system resources (that is, the processor, I/O devices, storage, and data sets on which a job can enqueue during its execution). It runs in the background and measures data over a time period. Reports can be printed immediately after the end of the measurement interval, or the data can be stored in SMF records and printed later with the RMF postprocessor. The RMF postprocessor can be used to generate reports for exceptions: conditions where user-specified values are exceeded.
2. Monitor II, like Monitor I, measures and reports the use of system resources. It runs in the background under TSO or on a console. It provides snapshot reports about resource usage, and also allows data to be stored in SMF records. The RMF postprocessor can be used to generate exception reports.
3. Monitor III primarily measures the contention for system resources and the delay of jobs that such contention causes. It collects and reports the data in real time at a display station, with optional printed copy backup of individual displays. Monitor III can also provide exception reports, but its data cannot be stored in SMF records.

RMF should be active in the system 24 hours a day. Run it at a dispatching priority above other address spaces in the system so that:

• The reports are written at the interval requested
• Other work is not delayed because of locks held by RMF.

A report is generated at the time interval specified by the installation. The largest system overhead of RMF occurs during the report generation: the shorter the interval between reports, the larger the burden on the system. An interval of 60 minutes is recommended for normal operation. When you are addressing a specific problem, reduce the time interval to 10 or 15 minutes. The RMF records can be directed to the SMF data sets with the NOREPORT and RECORD options; the report overhead is not incurred, and the SMF records can be formatted later.

For details on RMF Version 4, see MVS/ESA Resource Measurement Facility™ (RMF) Version 4 Program Summary and MVS/ESA Resource Measurement Facility (RMF) General Information.