2.9 An introduction to SMF88 records

< Day Day Up >

SMF Type 88 records contain information about usage of a log stream data for a system in a sysplex. Using the data from the Type 88 records can help you tune and perform capacity planning on your log streams.

Type 88 records summarize all a log stream's activity on a single system, as long as at least one address space is connected to the log stream on that system. If no System Logger write activity is performed against the log stream during a particular SMF interval, a record is produced showing zero for the various System Logger activity total fields.

The Type 88 record is produced for all log streams connected at the expiration of the SMF global recording interval. The creation of a Type 88 record is also triggered by the disconnection of the last connector to the log stream on that system.

There are some things you must remember about the Type 88 records however:

The Type 88 records only show activity from one system. If a log stream is used by more than one system, you must merge the information from all systems to get a comprehensive view of the use of that log stream
There are a number of subtype records produced by System Logger, but only one of them, the one dealing at the log stream level, has an IBM-provided formatter. Therefore, to determine what is happening at the structure level for structures containing more than one log stream, you need to merge the information from all log streams in that structure, from all systems in the sysplex.

In "SMF88" on page 260 you can find a discussion on how to set up for collecting Type 88 records. After the Type 88 records are collected, they can be sorted and analyzed using a tool; IBM ships one of these tools as a Samplib member called IXGRPT1. We'll discuss using IXGRPT1 in "IXGRPT1" on page 261.

IXGRPT1 provides one of the few ways to effectively tune your log streams for better performance. However, interpreting the report that is produced by the IXGPRT1 program is not a trivial task. In "SMF Type 88 records and IXGRPT1 program" on page 281 you can find a discussion on using the Type 88 data to tune System Logger performance as well as highlighting particular fields of interest in some of the application chapters.

< Day Day Up >