This section provides tuning tips for various components of z/OS or OS/390.
The first place to review is your CTRACE configuration. Ensure that all components are either set to MIN or OFF. To display the CTRACE options for all components on your system, issue the following command from the operator console:
D TRACE,COMP=ALLTo change the setting for an individual component to its minimum tracing value, use the following command (where 'xxx' is the component):
TRACE CT,OFF,COMP=xxxxThis will eliminate any unnecessary overhead of collecting trace information that is not being used. Often during debug, CTRACE is turned on for a component and not shut off when the problem is resolved.
Ensure that you are not collecting more SMF data than you need. Review the SMFPRMxx to ensure that only the minimum number of records are being collected.
Use SMF 92 or 120 only for diagnostics.
SMF Type 92 records are created each time an HFS file is opened, closed, deleted, and so forth. Almost every web server request references HFS files, so thousands of SMF Type 92 records are created. Unless you specifically need this information, turn off SMF Type 92 records. In the following example, we have disabled the collection of SMF type 92 records:
Example:
ACTIVE, DSNAME(SYS1.&.SYSNAME..SMF.MAN1;SYS1.&SYSNAME..SMF.MAN2;), NOPROMPT, REC(PERM), MAXDORM(3000), STATUS(010000), JWT(0510), SID(&SYSNAME;(1:4)), LISTDSN, SYS(NOTYPE(19,40,92)), INTVAL(30), SYNCVAL(00), SYS(DETAIL,INTERVAL(SMF,SYNC)), SYS(EXITS(IEFACTRT,IEFUJI,IEFU29,IEFU83,IEFU84,IEFU85,IEFUJV,IEFUSI))
You might find that running with SMF 120 records in production is appropriate, since these records give information specific to WebSphere applications such as response time for J2EE artifiacts, bytes transferred, and so forth. If you do choose to run with SMF 120 records enabled, we recommend that you use server interval SMF records and container interval SMF records rather than server activity records and container activity records. For details of the SMF 120 record, refer to Record Type 120 (78) - WebSphere for z/OS performance statistics.
For steps involved in controlling collection of SMF 120 records refer to Enabling SMF recording. To enable specific record types, use the administrative console to enable the following properties: