2. PERFORMANCE REPORTING ANALYSIS › 2.7 Graphic Analysis › 2.7.5 Paging Graphs › 2.7.5.4 Percent Busy for Local Page Data Sets

2.7.5.4 Percent Busy for Local Page Data Sets

GRAPHIC RESULTS

This graphic analysis provides a plot of percent device busy
for those devices which contain local page data sets.

ANALYSIS GUIDELINES

Local page data sets can experience paging loads from a
variety of sources:  demand paging, swapping, Hiperspace
migration, and virtual I/O.  Some of this paging traffic is
asynchronous, that is, no application is waiting for the
page's arrival before it can continue.  Some, however, is the
result of page faults and will cause the application to have
its processing suspended until the page has arrived in
processor storage.

Many people still tend to follow the rule of thumb that says
when your page pack reaches 35 percent busy, add another one.
For those people, we provide this chart.  However, the I/O
response time plot discussed in Section 2.7.5.2 provides a
better picture of the paging environment, and should be used
as the primary guide for analyzing and/or altering the paging
configuration.

The detailed behavior of the paging subsystem can be further
analyzed using the Auxiliary Storage Management analysis
reports described in Section 2.2.