Setting up a Monitor Definition › Samples and Observations

Samples and Observations

Starting with release 4.0 of CA MAT, there is a change in the definition of how samples are gathered.

Formerly, when you requested the number of samples to be gathered, the request was actually for the number of times CA MAT observes the complete activity of the address space. That is, the request was for the number of times the address space is swapped out, nondispatchable, delayed by LPAR/disabled work, actively using CPU, and waiting. Only the last two activities (actively using CPU and waiting) actually generate samples.

Because of this situation, CA MAT is introducing the concept of Observations and Samples. When you define how an address space is to be monitored (measured), you will request the number of times the address space activity is observed. Observations and observation rate are the only things you can influence, because you cannot predict beforehand the number samples that CA MAT will gather.

A sample within CA MAT reflects the activity of a TCB during an observation. The number of samples per observations can fluctuate tremendously from 0 to the total number of TCBs attached at the time of the observation.

So, an observation is the number and rate that CA MAT will examine the activity of the address space to be measured. A sample is created to reflect the activity of a TCB during an observation. There can be many samples gathered during an observation or 0 samples gathered, depending on the activity.