Understanding the CMF MONITOR Extractor
The Extractor is a component of CMF and other BMC Software products that samples data in your system, accumulates the data in CSA, and then writes that data to either SMF or other sequential data sets.
How the Extractor works
The figure below shows how the Extractor collects and records data.
Extractor data collection and recording functions
- Sampling data—The Extractor uses samplers to measure hardware usage (CPU, channel paths, I/O queuing, and I/O devices) and software activity (the SRM, paging, enqueue contention, TSO usage, and common storage allocations). A sampler is a program module that uses DIE (disabled interrupt exit), SRB (service request block), or SRM (System Resources Manager) methods of measuring data, For more information, see Sampling-data-and-producing-records.
- Controlling data collection—The function of each sampler that is running in your system is controlled by an Extractor control statement. (For more information, see the table in Numeric list of SMF record types.) Most of the Extractor statements have parameters that control the manner in which a particular sampler functions. In addition, there is a global Extractor control statement that has an overall effect on the way the Extractor operates and samplers function.
- Monitoring modes—The Extractor is actually made up of two distinct monitors that can be started, stopped, or modified independently, or they can both be running at the same time. The two monitors in the CMF Extractor are
- CPM (Continuous Performance Monitoring)—for low-resolution, long-duration monitoring
- IPM (Intermittent Performance Monitoring)—for high-resolution, short-duration monitoring
For more information about these monitoring modes, see When to use CMF MONITOR Extractor CPM and IPM modes.
- Writing records—The sampled data is collected in CSA for an interval of time that you define. (This time interval can be synchronized with SMF recording.) When the interval time expires, another function of the Extractor writes the data in CSA as records to SMF, or CMF data sets. For more information, see Writing-records.
How CMF MONITOR components use Extractor data
CMF MONITOR Online and CMFMON, the real-time components of CMF MONITOR, display the sampled data, as well as other data, directly from CSA, in windowed online views.
The CMF MONITOR Analyzer reads records from SMF or CMF data sets to produce historical batch reports.
When to use CMF MONITOR Extractor CPM and IPM modes
The Extractor provides you with a means for collecting two sets of data concurrently by operating in two modes.
By having two modes of the Extractor running at the same time, you can collect data in two different ways during the same time frame. The two modes are called CPM and IPM.
The Extractor in CPM mode functions separately from the Extractor in IPM mode. The Extractor in one mode can be started, stopped or modified independently of the Extractor in the other mode, and it can be running in both modes at the same time. For information about how to start, stop, or modify CPM and IPM modes, see Using-the-MODIFY-command-to-change-Extractor-operation.
CPM (Continuous Performance Monitoring)
The CPM mode is designed for low-resolution, consistent, long-duration monitoring.
This mode is intended primarily for long-term system measurement, and BMC Software recommends that you run this Extractor in CPM mode 24 hours a day at low sampling rates. The data collected in CPM mode is best used for daily reporting because of its consistency, and for long-term trend analysis because of its duration.
By setting the samplers to run at low sampling rates in this mode, CPU consumption is minimized over the long term. In addition, CPM-mode samplers that run 24 hours a day, but at low sampling rates, provide data that can be used best as a basis for identifying long-term performance trends in your system. However, this trend information can be developed only with continuous sampling.
A sample control statement for invoking the CPM-mode Extractor is shown in Using the CMFCPM00 control statement set.
IPM (Intermittent Performance Monitoring)
Because the CPM mode is normally used for low-frequency, long-duration data collection, you might want to use the IPM mode for short-term, intermittent, high-resolution monitoring of various resources.
By using two Extractors in this way, you can maintain the continuous sampling function while also obtaining the additional sampling data you need for another purpose. IPM is generally used to sample head movement, individual devices, and the like.
When you detect a trend that could be impacting performance, or when you have identified a distinct performance problem, you can use the IPM mode to run a set of samplers at high frequency rates. By concentrating your sampling of specific system resources at high intervals, the IPM data provides focused information about current performance problems for these resources. You can use the information from IPM mode sampling to determine specific causes of system performance difficulties.
BMC Software recommends that you run this mode only when necessary to minimize system impact. Initiating IPM mode to investigate specific areas of activity or to monitor specific devices during peak periods of activity should be at the discretion of your system programmer.
Because IPM mode (with more frequent sampling rates) has a higher overhead associated with it and provides concentrated sampling, the default Started Task JCL shipped with the Extractor does not initialize IPM mode at startup.
To start the IPM mode Extractor, you can either use the MODIFY command (for more information, see Using-the-MODIFY-command-to-change-Extractor-operation), or change the default setting on the MVS PAS PROC to DC=IPM (for more information, see Defining-Extractor-control-statements).
Two Extractor control statements are invalid in this mode: CSMON and EXTSUM.
A sample control statement for invoking the IPM monitor is shown in CMFIPM00 control statement set.
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