# Andy Hill
# http://virtualandy.wordpress.com/2009/02/05/get-vmstat-and-resource-allocation/
# Required: VI Toolkit
# Retrieve average CPU and RAM for specified VMs for elapsed period in hours

function Get-VMStat
{
	param( $VM,[Int32]$Hours = 1 )
 	$VM | Sort Name |
 		Select Name, @{N="CPU";E={[Math]::Round((($_ |
 		Get-Stat -Stat cpu.usage.average -Start (Get-Date).AddHours(-$Hours) -IntervalMins 5 -MaxSamples ($Hours*12) |
 		Measure-Object Value -Average).Average),2)}}, @{N="MEM";E={[Math]::Round((($_ |
 		Get-Stat -Stat mem.usage.average -Start (Get-Date).AddHours(-$Hours) -IntervalMins 5 -MaxSamples ($Hours*12) |
 		Measure-Object Value -Average).Average),2)}}
}

#Example Usage
# you will be asked for your VC server  
# PS> Get-VC 
# PS> Get-VMStat (Get-VM) -Hours 2160