Tandem Capacity Model (TCM) Manual

file. For more information, see “Transaction Count Table” (page 118) and the “Transaction
Count Table Versus Transaction Count File” (page 120).
9. Read Seconds per Transaction—Not modifiable
The apportioned number of disk read and disk write seconds consumed per transaction. The
Average Txn column contains the (weighted) average of disk seconds for each transaction.
Disk seconds are the number of seconds spent doing physical disk access, including seeks.
Seek seconds are apportioned by MeasTCM on the NonStop host system according to the
relative number of reads and writes performed.
The WA model distinguishes between disk seconds consumed by the various processes of a
transaction, such as the server, requester, disk, TMF, line handler, and other processes.
Disk read and write seconds are apportioned to transactions according to the userspecified
Apportionment Weights table.
Disk Write Workload Apportionment Screen
The Disk Write Workload Apportionment screen shows the apportionment of the disk write seconds
consumed by process categories to transactions. Figure 37 (page 112) shows a sample Disk Write
Workload Apportionment screen.
Figure 37 Disk Write Workload Apportionment Screen
Significant Rows
1. Disk Config—Not directly modifiable
Disk Config is the actual disk configuration that was measured for the sample, as determined
by MeasTCM on the NonStop host system. The configuration includes the number of logical
disk volumes, their configuration type, their write cache (WCE) configuration status and TMF
audit trail count. Valid disk write cache configuration status can be:
WCE enabled for disks that support WCEEnabled
WCE disabled for disks that support WCEDisabled
NA for disks that do not support WCENA
The WA model assigns an Aud disk configuration type if there are any audited transactions.
If none are audited and the number of logical and physical disks are equal, it assigns an
Unmirr disk type. Otherwise, the WA model assigns an Unaud disk type.
2. Fixed Write Sec—Not directly modifiable
Fixed Write Sec is the total number of CPU seconds consumed per second by process categories
of type F (fixed). This number is not included in the CPU and disk consumption of individual
transactions but does affect the total CPU and disk utilizations. A category should be defined
112 Workload Apportionment Model