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What settings control the DDF enclave portion of CPU usage?

Question & Answer


Question

If I am running DB2 under WLM goal mode, what settings control the DDF enclave portion of CPU usage? Where can I find useful information about using Workload Manager with DB2?

Answer

First, look at the White Paper, WLM Migration Guide and Checklist, reference number 8525691F0049A5F6 . This document helps you plan the migration to WLM goal mode and lists supporting documents to assist you in customizing your system. For DB2®-specific performance information for WLM, see the DB2 Administration Guide for your version of DB2 at the DB2 for z/OS® and OS/390® Library Web page.

When running DB2 in a WLM goal mode environment, you must first establish service classes for the DB2 started tasks, which includes the ssnmDIST address space. It is recommended that the ssnmDIST address space have the same service class as the other DB2 started address spaces, ssnmDBM1 (the DB2 database services address space) and ssnmMSTR (the DB2 system services address space). This service class must be defined with a velocity goal and an appropriate level of importance. It must not have multiple periods.

After work has started in the ssnmDIST address space, DB2 calls WLM to classify the particular task into an enclave. To manage DDF enclaves, you must use the MVS WLM classification rules panel to specify how DDF subsystem types of work with variations of work qualifiers are to be related to the set of services classes within your active MVS WLM policy. You must set a default service class for any DDF work that does not meet any of the classification rules. If you do not set a default service class, any DDF work that does not match any of the qualifications within the DDF subsystem type classification rules defaults to an importance of SYSOTHER, which has a very low priority.

When setting up the service classes for the DDF work, you can utilize all of the WLM goal types: percentile response time, average response time, velocity, and discretionary. You can also create service classes that incorporate period switching if and only if the DB2 initialization parameter, CMTSTAT, has been set to INACTIVE. If CMTSTAT has been set to ACTIVE, only velocity goals can be used. See "Using Workload Manager to set performance objectives" in the DB2 Administration Guidefor more information.

For more information about setting goals for users, see z/OS MVS Planning: Workload Management at the z/OS Library Web page.

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Historical Number

84403;082;000

Document Information

Modified date:
16 June 2018

UID

swg21041130