Tandem Capacity Model (TCM) Manual

to FALSE, TCM assumes that all batch jobs restart when completed. No matter how long batch
jobs actually take, they are all considered to be running simultaneously all of the time. The
default value is TRUE.
5. Query Transaction OLTP-> Batch response Time CPU pathlength threshold—Directly Modifiable
This option is the point at which a query transaction is considered either an OLTP or batch
transaction. The default setting is two seconds. Small demand queries taking less than two
seconds are considered OLTP transactions. Large demand queries taking longer than two
seconds are considered batch transactions. Any TCM user can modify this parameter.
6. Audit Write Ceiling—Directly Modifiable
Audit Write Ceiling is the maximum number of audit writes per second. The model provides
a default value, but a TCM administrator or super user can modify it if a more appropriate
value is available.
7. # Commits per Txn—Directly Modifiable
# Commits per Txn is the number of TMF transactions in a business transaction. A business
transaction is sometimes made of more than one TMF transaction. That is, it has more than
one begin-end transaction statement pair. Its value affects TCM response time estimates.
NOTE: This field applies to all audited transactions in the model. Its default value is one.
8. Audit Disk Configuration—Directly Modifiable
Audit Disk Configuration is the assumed disk configuration for audit disk. The specified
configuration must be one of the following: Mirr (mirrored), Unmirr, (unmirrored) or Serial.
9. Response Time Gamma Factor—Directly Modifiable
It is the Disk Rotation Factor, that is, Number of Disk Rotations per Second. One quarter of
the time it takes to do a rotation is added in as part of the Response Time formulas for parallel
writes. This extra factor is needed because parallel writes never occur truly simultaneously,
one disk taking slightly longer than the other.
CPU Factors Screen
The CPU Factors screen is used to set the CPU conversion factors used by the Performance model
and to add new CPU types, RVUs and factors to model systems with theoretical CPU types (along
with their IPU count). Figure 48 (page 150) shows a sample CPU Factors screen.
CPU Factors Screen 149