What does Interval, Sample and QoS Interval mean in the CDM configuration window?
Article ID: 39405
Updated On: 10-05-2023
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Explanation on how CDM Control properties work.
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This example is for CPU properties
Interval, means how often the system checks for data.
Samples, means how many data points are averaged on a rolling basis.
Qos Interval, means how often the qos data actually gets written to the database.
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In this example, Interval is 5 minutes, Samples is 5, and QoS interval is 2.
Data is written every 10 minutes (Interval x QoS Interval) into the database.
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How QoS gets written to the database.
ie. CPU properties: interval 5 min, samples 5, QoS Interval 2.
# time cpu sample (how number is calculated)
a 1:00:00 50% ( a )
b 1:05:00 51% ( (a+b)/2 ) qos to database
c 1:10:00 50% ( (a+b+c)/3 )
d 1:15:00 50% ( (a+b+c+4)/4) qos to database
e 1:20:00 50% ( (a+b+c+d+e)/5 )
f 1:25:00 75% ( (b+c+d+e+f)/5 ) qos to database
g 1:30:00 75% ( (c+d+e+f+g)/5 )
h 1:35:00 50% ( (d+e+f+g+h)/5 ) qos to database
i 1:40:00 50% ( (e+f+g+h+i)/5 )
j 1:45:00 51% ( (f+g+h+i+j)/5 ) qos to database
"Samples" affects the averaging applied to the measurements used to compare against thresholds. So in your example, you have samples set to 3, interval set to 5 and QOS interval set to 1. Then if your measures were 90 @ 5 minutes, 95 @ 10 minutes and 100 @ 15 minutes, you have 3 QOS values sent at that point with values 90, 95, and 100. By the default settings, after you have "samples" number of samples, the probe will start comparing with the thresholds and that first comparison will be (90+95+100)/3 or 95%. If at 20 minutes you have another 100% QOS your next comparison will be (95+100+100)/3 or 98.3%. And if you are still at 100% at 25 minutes in, your next comparison would be (100+100+100)/3 or 100%.
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