Can I modify Real-Time Performance Chart sampling

[mcmark]

I am preparing a demonstration and want to show Real-Time resource allocations using the vSphere performance charts. Unfortunately, the default sampling rate and averaging periods are not optimal for showing resource allocations in our demonstration. Can anyone tell me if there is an easy way to modify these default values?

The sampling rate for Real-Time charts is 20 seconds which is probably OK but I would LIKE to change it to 10 seconds. The main area of concern however is the number of samples over which that the average is calculated. This value seems very high (I think I saw 300 in a document). Because this number is very high, changes in allocations that I make say every minute (for demonstration purposes), don't really show up very well in the vSphere performance charts. For example:

If my host has had 10 GB active memory for the last 5 minutes and my demonstration deallocates a huge portion of that memory suddenly, the performance chart averages the sudden deallocation with the last say 10 minutes of data and shows a gradual decline in the memory allocations.

This behavior is probably what is desired in a real monitoring system BUT for my demonstration, I would like to show a more realistic view of the resource allocations using the vSphere performance charts. This could be accomplished if the sampling rate and averaging periods are configurable.

All help is greatly appreciated.

[monisiqbal]

If you are monitoring/using vCenter then yes. If you are are using a server directly like ESX then you cannot modify the sampling interval.

For vCenter, have a look at this thread which I posted to ask about changing the value from vSphere client for a vCenter server.

[mcmark]

Thanks for your response monisiqbal. Unfortunately, the document appears to only specify how to change HISTORICAL sampling rates which only go as low as 1 minute. I am using the REAL-TIME charts which currently sample at 20 second intervals but I would like to be able to modify this rate while still seeing REAL-TIME information.

Any other suggestions or did I miss something in the document that I should have seen?

[monisiqbal]

You cannot change the sampling time for REALTIME interval. In vCenter there are 4 additional intervals in addition to the realtime interval which essentially is the interval of the host system (therefore can't be changed from 20 secs). These intervals are:

Day (1 - 5 days, statistic interval: 1 - 5 minutes)

Week (1 Week, statistic interval: 30 minutes)

Month (1 Month, statistic interval: 2 hours)

Years (1 - 5 Years, statistic interval: 1 day)

[monisiqbal]

one additional info: the realtime statistics only remain for 1 hour and are not saved to the vCenter database.

[mcmark]

This is what I was afraid of.

It would be nice if VMware had allowed modification to say 10 seconds which would keep 30 minutes of real-time data.

Also wondering if you know why the real-time charts take soooo long to respond when I deallocate memory. When I deallocate a big group of memory, the chart kind of decays over a period of 5 minutes. I thought this was because of sample averaging but if that was so, I would think that same behavior would happen when I allocated the big group of memory. In the allocation case, the chart has a pretty steep step.

[monisiqbal · Accepted solution]

I on the other hand think it's good that they don't allow modifying realtim metrics. It's good for my purpose

I don't know about the slow response due to memory alloc/dealloc.

btw if you think the above answer solved your issue, you could mark it as answered.