Tandem Capacity Model (TCM) Manual

model, the value of the Disk Write Cache is automatically set to the default write cache value
corresponding to the selected Disk model.
6. TMF audit trails—Constraint Modifiable
TMF audit trails depict the number of audit trails used in actual measurement. The value for
the TMF audit trail constraint field can be between 1 and 16. The number of audit trails
required for planned data is based on the TMF seconds required for planned transactions
and the audit write ceiling value for each audit trail and type of audit trail configuration
(mirrored, unmirrored or serial).
7. Avg Online Util—Constraint modifiable
Avg Online Util is the average percentage utilization of actual and planned CPUs and disks
for online transactions. These utilization values cannot exceed the values in the Constraint
fields, if values are entered. To enter a utilization percentage in a Constraint field, type any
whole number between 1 and 99.
8. Avg Online Resp Time—Constraint modifiable
Avg Online Resp Time is the host response time for the actual and planned average transaction
for online transactions. You can enter the maximum chosen value for the estimated host response
time in the Constraint field. This field is particularly useful if a known host response time
requirement for the average (90, 95, or 99%) transaction must not be exceeded. If a value
is entered, the Consumption model estimates the number of CPUs and disks so that the estimated
host response time for the average (90, 95, or 99%) transaction is below this value, if possible.
Use the Select Response Time Method on the Options tab to set the type of response time
wanted. Note that the average (90, 95, or 99%) online response time is a weighted average
of the individual OLTP transactions average (90, 95, or 99%) response times.
9. Avg Batch Resp Time—Constraint modifiable
Avg Batch Resp Time is the host response time for the actual and planned average transaction
for batch transactions. You can type the maximum desired value for the estimated host response
time in the Constraint field. This field is particularly useful if a known host response time
requirement for the average batch transaction must not be exceeded. If a value is entered,
the Consumption model estimates the number of CPUs and disks so that the estimated host
response time for the average batch transaction is below this value, if possible. Note that the
average batch response time is an unweighted average of the individual response times of
the batch transactions. Batch times longer than 999 hours (41.625 days) are displayed as
999 hours.
10. Sample File—Not directly modifiable
The input file name used to work with performance model.
11. Sample Date—Not directly modifiable
Is the creation date of the input file which used to work with the performance model.
12. Disk Partitions — Disk partitions are the actual, constrained, and planned partition configuration
for SSD disks. Disk partition specifies whether the SSD disk is partitioned or not. If partitioned,
it also specifies the number of partitions. For non SSD disks, this field is NA (not applicable).
Whenever the user selects the SSD model, the value of the disk partition is automatically set
to one, and enables users to select values from 1 to 8.
142 The Performance Model