Setting up SMF requires your installation to decide what kind of
records it wants SMF to produce or what information it wants SMF to
gather. Then you can make decisions about how to set SMF up to meet
these requirements. You'll also want to consider the following in
planning your SMF configuration:
- What records must SMF produce to give you the information your
installation wants?
- What is the environment SMF will run in and how many jobs run
through the system? (The number of records generated by SMF depends
on the number of jobs.)
- Are you running program products (such as RMF™ or DB2®)
that might require special considerations for SMF? (See Special considerations for DB2, JES3, and RMF.)
- What is the impact of the system configuration, particularly the
type and degree of multiprogramming?
- How much contention is there for the resources that SMF needs?
Once you've considered some of the basics above about
what you want SMF to do in your installation, your next decision is
whether you want to write your SMF records to log streams or to SMF
data sets, or both.
- If you use SMF data sets, SMF will write records to the
SMF data sets you allocate. The size of the data that the system can
write to SMF data sets is constrained by the VSAM control interval
size - SMF can only write one control interval at a time. See Setting Up and Managing SMF Recording to Data Sets.
- If you use SMF logging, SMF will write records to the system
logger managed log streams you set up. SMF can write much larger chunks
of data to the log stream than it can to SMF data sets. This has the
potential to make writing SMF records faster, which could mean collecting
more data.
SMF logging also allows you to group different SMF record
types into different log streams defined for different purposes. For
example, you might want a log stream for job-related SMF data and
one for performance SMF data. What's more, you can write a single
record to multiple log streams. Record 30, the common address space
work record, for example, might well fit into both the job-related
log stream and the performance log stream.
You can set up either:
- Coupling facility log streams, where data is stored in a coupling
facility structure and then offloaded to DASD.
- DASD-only log streams, where data is stored in local storage buffers
and then offloaded to DASD.
See
Setting Up and Managing SMF Recording to Logstreams
Now that you've made some basic decisions, use the
following topics to set up SMF to meet your installation's requirements: