Question on collection Levels

[gogogo5]

About 2 months ago I configured our VC to use a Statistics Collection Level of 2. The description it gives mentions that maximum and minimum rollup types are excluded[/b].

When selecting a performance graph and choosing, for example, CPU - Past Week from Chart Options for the cluster or individual VM the performance results does show figures for Latest, Max, Min and Average.

So why are there figures showing for Max and Min when the above says it is excluded?

[jlauro]

You are seeing the values based on the average sample per period.

If you had full statistics, you could select cpu usage (Maximum Rate) and get a minimum and maximum of that, which would be calculated based on the smallest time interval for each of the larger time intervals.

Real time is per minute. Week is stored per 15 minute.

So you only get per average of per 15 minute, and not per max minue per 15 minute, and you Max is the max of the average per 15 minutes of cpu. You don't get the max per minute.

Looking at one random guest of one of our busier servers on past week...

CPU Usage (average/Rate): Max 44.2, Min 3.82, average 16.81

CPU Usage (maximum/rate): Max 92.16, Min 10.52, average 35.91

I assume you can only get CPU Usage (average/Rate), and not CPU Usage (maximum/rate).

[gogogo5]

Yes, I only see CPU Usage (average/Rate), and not CPU Usage (maximum/rate).

I think I am getting it but could you clarify something. So we are saying that for Past Week samples are taken every 15 minutes therefore giving 672 samples.

1. So the Average value would be the sum of all samples divided by 678?

2. The Maximum (average) value is just the maximum figure from all the 678 samples?

[jlauro · Accepted solution]

Right. Except technically each of the 678 samples is an average of the 15 1 minute samples. Minor difference, but does flatten your data down as you loose resolution going from day to week to month to year...

If you had the Mximum/rate you could see the maximum rate of 10170 samples instead of just the maximum rate of 678 15 minute averages.

[gogogo5]

thanks.