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Appendix B Service Level Agreements
This enhancement to the SCOPEXL performance data collector adds a new
application metric to an existing field of the application record. No
log file format changes are required.
This metric can be used for service level agreements that contract for a
certain percentage of terminal response times to be at or below a given
level. For example, an agreement might specify that 95% of the terminal
response times for the Order Entry application will be 1 second or less.
Some applications base service levels on the first-response time, others
use the response-to-prompt times. This enhancement allows you to use
either method or a combination of methods.
There are several rules:
1. The system manager must enter the agreed-upon response time values
into the PARM file for those applications of interest. Each
application may have different service levels, if desired.
2. The collector will examine all of a process's applications once a
minute. If the process's average response time exceeds the
first-response or response-to-prompt service level value for that
interval, all transactions performed by that process are
considered as "failing to meet the service level agreement."
3. At the end of each five-minute collection period, the number of
transactions that met the service level agreement--the
application's first-response and response-to-prompt times were at
or below the agreed upon values--is logged as a percentage of the
total transactions in the application.
You can easily assess conformance to a service level agreement by
plotting the percentage of transactions that met the agreed upon values
over time. A service-level violation occurs each time this percentage
falls below the threshold value.
By monitoring the percentage value before it drops below the threshold
value, you might be able to avoid violations of the agreement.