SMF generates records that describe changes in the system configuration:
- At IPL for online devices (types 0, 8, 19, and 22)
- When a device is added to the configuration (types 9 and 10)
- When a device is removed from the configuration (type 11)
- When a processor, channel path, storage device moves online or
offline (type 22)
In addition to these records, operations management can use specific
information in other SMF records to report configuration statistics.
The examples that follow show this use of SMF.
Device and channel loading
From SMF records,
an installation can obtain the total problem program EXCP counts by device and
by channel over a given reporting period. (See EXCP Count for
a detailed explanation of EXCP counts and their use in SMF records.)
While this summary does not provide a true picture of the I/O load
distribution, it might be helpful in identifying a gross loading imbalance
among various devices or channels.
Concurrent device use
An installation can
combine the data in the SMF step termination records to report the
number of devices per device type that problem programs used during
specified intervals. By using this report with the RMF™ device activity records (type 74), an installation
can identify periods of the day when the percentage of problem program
device use was exceptionally high or low. Further evaluation might
show the cause of concurrent device use. If, for example, no more
than 12 of the available 16 tape drives are ever in use at the same
time, one of the following situations might be responsible:
- Job classes are conflicting.
- Too few initiators are started.
Note: You would find it very difficult to perform tape-allocation
analysis for long-running started tasks that dynamically allocate
and deallocate tape drives. SMF does not record such information.
HSM and DB2® are examples of
such started tasks.