With the vSphere 5 licensing buzz from the past days and the incredibel number of hits on my Query vRAM post, I considered that a script to help you discover your memory overallocations might be useful.
The script uses the metric mem.usage.average to find out what amount of it’s allocated memory a guest is actually using. The script produces a report that will help you to determine which guests would be good candidates to lower their memory allocation.
A quick post that is triggered by a tweet from @GernotNusshall I saw passing today. He wanted to know how to find the maximum IOPS values over the last 5 minutes for a number of VMs. The IOPS values are readily available from the vSphere statistics but the problem is that the values are returned as summation values over the measuring interval and that you have a read and a write value.
An ideal job for PowerShell to get the values Gernot was after.
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As most of you should know VMware is organising a scripting contest, called Script-O-Mania. For those of you that haven’t submitted anything yet, hurry up. The closing date is tomorrow (March 15th 2010).
After some reflection I decided to go for a performance monitoring script. I wanted to have the vCenter client performance tab, without having to pay for the vCenter Agent license. And I wanted to offer some of the functionality that esxtop provided on the classic ESX systems.
That’s where my PSTop v1 script came to be.
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In PowerCLI & vSphere statistics – Part 1 – The basics I briefly mentioned instances. In this post I’ll go a bit deeper into that subject.
And to demonstrate it all I will use part of the esxtop post on Yellow Bricks. In that post Duncan compiled, from various sources, a number of “common sense” thresholds that you can use in esxtop to show you possible problems with your hosts and/or guests.
Since I’m not sitting 24/7 behind an ESX/ESXi console, I looked for a way to let PowerCLI/PowerShell do that for me 
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The end of my previous post in this series, see PowerCLI & vSphere statistics – Part 1 – The basics, showed how you could get the statistical values for a specific day.
Depending on the point in time for which you request the values, the sampling interval will be different. For example Historical Interval 2 will return values measured over 30 minute intervals. See also the schematic I included in the previous post.
This sample interval is not always what you want for your reports. Suppose you want to always report hourly values and only for working hours during business days. This post will show you how to accomplish that.
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Another popular subject in the VMTN PowerCLI community are statistics. Quite often it’s not entirely clear to the user what is available, how the data can be extracted and how PowerShell/PowerCLI can be used to convert the raw metrics into usable reports.
Before you can fully use all that is available, there are a few key concepts that you should understand.
In this series I will try to explain some common questions.
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