Average CPU usage with get-stat

[TheVMinator]

With get-stat I can get average CPU Usage in MHz using the usagemhz metric.

however, by default the maximum and minimum in MHz is not included in the data points from 2 months ago.  That is fine if I just want the average but I also need average peak values.  Is average peak CPU usage possible with powerCLI?

The thing is that when you are getting these averages and you only have one day or one week worth of data it isn't enough to really give you a true picture- you need 2-3 months.  Haw can I get to that with PowerCLI?

[LucD]

You can get the minimum and maximum of the averages for the past 2 months like this for examle.

$entity = Get-vm -Name MyVM
$stat = "cpu.usagemhz.average"

$start = (Get-Date).AddMonths(-2)

Get-Stat -Entity $entity -Stat $stat -Start $start |
Measure-Object -Property Value -Minimum -Maximum -Average

But note that, due to aggregation, these values will not be the same as the actual minima and maxima of the collected data.

Depending on why you want to use the values, this approximation might be sufficient though.

[TheVMinator]

OK thanks for the great info.  I think really I need two things:

First I need to take a group of VMs and see what the average CPU usage is in MHz.  It looks like just the regular

cpu.usagemhz.average

is just fine for that, as per this great website article I found

http://www.lucd.info/2009/12/30/powercli-vsphere-statistics-part-1-the-basics/

However the second thing I need is akin to the concept of the 95th percentile in vCOps.  The concept is that you are looking at your average usage, and then you are looking to see what happens during peak periods in your enviornment.  The two questions are:

What should I expect my VMs to demand normally

What should I be prepared for my VMs to demand during a peak usage period (example - a large accounting firm with 5000 vms during quarter end processing).

I want to get the average and the "average peak" for my cpu.usagemhz

From what I can see, powerCLI is great for the average.  Can it do the average peak such as a 95th percentile?

(BTW looking forward to this new performance reporting with PowerCLI book that I see coming out on Amazon)

[LucD]

Ok, I think I see what you want to do.

The following code will, per VM, display the average CPU usage and the 95 percentile CPU usage over the last 7 days.

Note that this is a rather simple way to calculate the 95 percentile (in the book there should be more elaborate methods).

$start = (Get-Date).AddDays(-7)
$stat = "cpu.usagemhz.average"
$vm = Get-VM

Get-Stat -Entity $vm -Stat $stat -Start $start  |
Group-Object -Property {$_.Entity.Name} | %{
    $calc = $_.Group | Measure-Object -Property Value -Average 
    New-Object PSObject -Property @{
        VM = $_.Group[0].Entity.Name
        AvgCPUMhz = [Math]::Round($calc.Average)
        Avg95pCPUMhz = ($_.Group | Sort-Object -Property Value )[[math]::Round($calc.Count * 0.95)]
    }
} | Select VM,AvgCPUMhz,Avg95pCPUMhz

[TheVMinator]

OK great thanks.  This report works as I run it but inputting a VM or set of VMs and report on this one metric for the set of VMs.  In my case 'm trying to actually run this report in such a way that I am listing a set of VMs, then for each VM caclulating a certain set of properties, in which this is one.

For example:

$stat = "cpu.usagemhz.average"

$start = (Get-Date).AddDays(-30)

get-vm myvm | select name, numcpu,

@{N="Average CPU Usage";E={

  Get-Stat -Entity $_ -Stat $statCPUMHzAvg -Start $start  |

  Group-Object -Property {$_.Entity.Name} | %{

  $calc = $_.Group | Measure-Object -Property Value -Average 

  New-Object PSObject -Property @{  

  AvgCPUMhz = [Math]::Round($calc.Average)  

   }

   } | Select AvgCPUMhz

  }}

1. Is it possible to modify the report to do this?
Also,  The output of the report is

@{AvgCPUMHz=150}

instead of just

150

2. How can I remove the @{} from the output?

Thanks!

[LucD · Accepted solution]

1. You can easily adapt the Get-VM cmdlet to produce the result for 1 or a limited set of the VM

For example:

Get-VM -Name MyVM | Select ...

will return the result for 1 VM called MyVM

If you do

Get-VM -Name My* | Select ...

it will return results for all VMs whose name starts with "My"

2. That's because the Select-Object produces a hash table, and PowerShell by default displays hash tables like that.

To only get the actual value change the last Select like this

...

} | Select -ExpandProperty AvgCPUMhz

...

[TheVMinator]

works great - thanks again.