TPDC Manual (G06.24+)

Using the SPAM Performance Data Charts and
Reports
Tandem Performance Data Collector (TPDC) Manual—526357-001
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Disc File I/O Activity Distribution (DFIODST)
•
A file’s contribution to a volume’s cache hits/physical I/Os
•
Estimated CPU utilization of the primary disk process in servicing cache and I/O
activity for the file
•
Estimated utilization of the primary disk drive servicing I/O activity for the file
These last two items represent what the chart calls the “Estimated Utilization Shift,”
that is, by how much the CPU and primary drive utilizations would decrease if the file
were moved off its current volume (and conversely, by how much they would increase
for wherever the file subsequently resides).
Interrupt time is factored into the disk process CPU time, apportioned according to
message traffic. The query accepts a TPRODUCE option IOFACTOR that (like TCM)
indicates by how many times a physical I/O (driver call minus cache hit) is more
expensive than a cache hit. Its default value (like that for TCM) is 2. It also accepts the
standard option EXCLUDE, which in this case excludes files whose proportions of their
volumes’ total of either cache hits or physical I/Os is less than (EXCLUDE * 10)
percent.
This chart uses the GLOBINFO, DGLOBAL, CPU, and DISCINFO entities.
Parameters used are:
•
LID—specifies the Measure Load ID
•
EXCLUDE—specifies a value under which to exclude the number of requests per
second
•
IOFACTOR—specifies relative cost, physical I/O versus cache hit
•
SECTION—specifies the report section number
The chart is sorted in descending DSOPNSUM driver-call order.