IBM System Management Facilities

IBM System Management Facility (SMF) is a component of IBM's z/OS for mainframe computers, providing a standardised method for writing out records of activity to a file (or data set to use a z/OS term). SMF provides full "instrumentation" of all baseline activities running on that IBM mainframe operating system, including I/O, network activity, software usage, error conditions, processor utilization, etc.

For other uses, see SMF (disambiguation).

One of the most prominent components of z/OS that uses SMF is the IBM Resource Measurement Facility (RMF). RMF provides performance and usage instrumentation of resources such as processor, memory, disk, cache, workload, virtual storage, XCF and Coupling Facility. RMF is technically a priced (extra cost) feature of z/OS. BMC sells a competing alternative, CMF.

SMF forms the basis for many monitoring and automation utilities. Each SMF record has a numbered type (e.g. "SMF 120" or "SMF 89"), and installations have great control over how much or how little SMF data to collect. Records written by software other than IBM products generally have a record type of 128 or higher. Some record types have subtypes - for example Type 70 Subtype 1 records are written by RMF to record CPU activity.

SMF record types

Here is a list of the most common SMF record types:

  • RMF records are in the range 70 through to 79. RMF's records are generally supplemented - for serious performance analysis - by Type 30 (subtypes 2 and 3) address space records.
  • RACF type 80 records are written to record security issues, i.e. password violations, denied resource access attempts, etc. TopSecret, another security system, also writes type 80 records. ACF2 provides equivalent information in, by default, type 230 records but this SMF record type can be changed for each installed site.
  • SMF type 89 records indicate software product usage and are used to calculate reduced sub-capacity software pricing.
  • DB2 writes type 100, 101 and 102 records, depending on specific DB2 subsystem options.
  • CICS writes type 110 records, depending on specific CICS options.
  • Websphere MQ writes type 115 and 116 records, depending on specific Websphere MQ subsystem options.
  • WebSphere Application Server for z/OS writes type 120. Version 7 introduced a new subtype to overcome shortcomings in the earlier subtype records. The new Version 7 120 Subtype 9 record provide a unified request-based view with lower overhead.

Evolving records

The major record types, especially those created by RMF, continue to evolve at a rapid pace. Each release of z/OS brings new fields. Different processor families and Coupling Facility levels also change the data model.

SMF data recording

SMF can record data in two ways:

  • The standard and classical way: Using buffers the SMF address space, together with a set of preallocated datasets (VSAM datasets) to use when a buffer fills up. The standard name for the datasets is SYS1.MANx, where x is a numerical suffix (starting from 0).
  • The relatively new way: Using log streams. SMF utilizes System Logger to record collected data, which improves the writing rate and avoids buffer shortages. It has more flexibility, allowing the z/OS system to straightforwardly record to multiple log streams, and (using keywords on the dump program) allowing z/OS to read a set of SMF data once and write it many times.

Both the two ways can be declared for the use, but only one is used at a time in order to have the other as a fallback alternative.

This data is then periodically dumped to sequential files (for example, tape drives) using the IFASMFDP SMF Dump Utility (or IFASMFDL when using log streams). IFASMFDP can also be used to split existing SMF sequential files and copy them to other files. The two dump programs produce the same output, so it does not involve changes in the SMF records elaboration chain, other than changing the JCL with the call of the new dump utility.

SMF data collection

SMF data can be collected through IBM Z Common Data Provider. IBM Z Common Data Provider (ZCDP) collects SMF data, transforms it in a consumable format and then sends the data to analytics platforms for further analysis. ZCDP collects SMF data in the following three ways:

  • In log stream mode with SMF in-memory buffer

When SMF is run in the log stream mode, ZCDP can be configured to collect SMF from the SMF in-memory buffer with the SMF real-time interface.

  • In data set recording mode

When SMF is run in the data set recording mode, ZCDP collects and streams SMF data via a set of SMF user exits.

  • In batch mode

The System Data Engine component of ZCDP can be run stand-alone in batch mode to read SMF data from a data set and then write it to a file. The System Data Engine batch jobs can be created to write SMF data to data sets and send SMF data to the Data Streamer.

References
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