############
# Get-HAClusterSize 
# by Hugo Peeters
# http://www.peetersonline.nl
# Please leave this header intact when distributing
# NOTE: rename the file to .ps1
########

###########
# Variables
###########

# Situation specific (adjust values to suit your environment)
$VCServerName = "vcserver.domain.local"					# The FQDN of your Virtual Center server
$ClusterName = "my HA cluster"							# The name of the cluster

# General (do not modify)
$DefaultCPURes = 256									# Default Minimum CPU reservation for HA calculations = 256 MHz
$DefaultMemoryRes = 256									# Default Minimum Memory reservation for HA calculations = 256 MB

##################
# Script execution
##################

If ((Get-PSSnapin VMware.VimAutomation.Core) -eq $null)
{
	Add-PSSnapin VMware.VimAutomation.Core
}
$VC = Get-VIServer $VCServerName -ErrorAction Stop
Write-Progress -Activity "Processing cluster" -Status $ClusterName
$Cluster = Get-Cluster $ClusterName
$ClusterAdv = Get-View $Cluster.Id
$CurrentFailoverLevel = $ClusterAdv.summary.CurrentFailoverLevel
$vmCPUMinMHz = ($ClusterAdv.configuration.dasconfig.option | Where {$_.Key -eq "das.vmCpuMinMHz"}).Value
If ($vmCPUMinMHz){$MinCPUReservation = $vmCPUMinMHz}
Else {$MinCPUReservation = $DefaultCPURes}
$vmMemoryMinMB = ($ClusterAdv.configuration.dasconfig.option | Where {$_.Key -eq "vmMemoryMinMB"}).Value
If ($vmMemoryMinMB){$MinMemoryReservation = $vmMemoryMinMB}
Else {$MinMemoryReservation = $DefaultMemoryRes}

# Process VMs
Write-Progress -Activity "Processing VMs" -Status "Getting all VMs"
$VMs = Get-VM -Location $Cluster | Sort-Object Name
$myVMcol = @()
$i = 1
$j = $VMs.length
ForEach ($VM in $VMs)
{
	Write-Progress -Activity "Processing VMs" -Status $VM.Name -PercentComplete (100*$i/$j)
	$myVMobj = "" | Select-Object Name, CPUSlot, MemSlot
	$myVMobj.Name = $VM.Name
	$VMadv = Get-View $VM.Id
	If ($VMadv.resourceconfig.cpuallocation.reservation -eq 0){$CPURes = $MinCPUReservation}
	Else {$CPURes = [math]::Round($VMadv.resourceconfig.cpuallocation.reservation/1000000,0)}
	If ($VMadv.resourceconfig.memoryallocation.reservation -eq 0){$MemRes = $MinMemoryReservation}
	Else {$MemRes = [math]::Round(($VMadv.resourceconfig.memoryallocation.reservation / 1MB),0)}
	$myVMobj.CPUSlot = ($VM.NumCPU * $CPURes)
	$myVMobj.MemSlot = [math]::Round((($VMadv.runtime.memoryoverhead / 1MB ) + $MemRes),0)
	$myVMcol += $myVMobj
	Clear-Variable CPURes
	Clear-Variable MemRes
	$i++
}
$MaxCPUSlot = ($myVMcol | Sort-Object CPUSlot -Descending | Select-Object -First 1).CPUSlot
$MaxMemSlot = ($myVMcol | Sort-Object MemSlot -Descending | Select-Object -First 1).MemSlot

# Process VMHosts
Write-Progress -Activity "Processing VMHosts" -Status "Getting all VMHosts"
$VMHosts = Get-VMHost -Location $Cluster | Sort-Object Name
$myVMHostCol = @()
$k = 1
$l = $VMHosts.length
ForEach ($VMHost in $VMHosts)
{
	Write-Progress -Activity "Processing VMHosts" -Status $VMHost.Name -PercentComplete (100*$k/$l)
	$myVMHostObj = "" | Select-Object Name, CPU, CPUSlots, Memory, MemSlots
	$myVMHostObj.Name = $VMHost.Name
	$VMHostAdv = Get-View $VMHost.Id
	$myVMHostObj.CPU = [math]::Round(($VMHostAdv.hardware.cpuinfo.numcputhreads * $VMHostAdv.hardware.cpuinfo.hz / 1000000),0)
	$myVMHostObj.CPUSlots = [math]::Floor($myVMHostObj.CPU / $MaxCPUSlot)
	$myVMhostObj.Memory = [math]::Round(($VMHostAdv.hardware.memorysize / 1MB),0)
	$myVMHostObj.MemSlots = [math]::Floor($myVMHostObj.Memory / $MaxMemSlot)
	$myVMHostCol += $myVMHostObj
	$k++
}

# Calculations
$TotalCPUSlots = ($myVMHostCol | Sort-Object CPUSlots | Select-Object -First ($myVMHostCol.Length - $Cluster.HAFailoverLevel) | Measure-Object -Property CPUSlots -Sum).Sum
$TotalMemSlots = ($myVMHostCol | Sort-Object MemSlots | Select-Object -First ($myVMHostCol.Length - $Cluster.HAFailoverLevel) | Measure-Object -Property MemSlots -Sum).Sum
If ($TotalMemSlots -lt $TotalCPUslots){$capacity = $TotalMemSlots}
Else {$capacity = $TotalCPUslots}
$available = ($capacity - $VMs.Length)

# Output
Write-Host "================================="
Write-Host "Your heaviest VM in terms of CPU usage is considered to be:"
$myVMcol | Sort-Object CPUSlot,MemSlot -Descending | Select-Object -First 1 | Format-Table -AutoSize 
Write-Host "Your heaviest VM in terms of Memory usage is considered to be:"
$myVMcol | Sort-Object MemSlot -Descending | Select-Object -First 1 | Format-Table -AutoSize 
Write-Host "Your cluster has the following VMHosts:"
$myVMHostCol | Format-Table -AutoSize
Write-Host "If you should lose your heaviest VMHost, you would have left:"
Write-Host "Number of CPU slots:    $TotalCPUSlots"
Write-Host "Number of memory slots: $TotalMemSlots"
Write-Host ""
Write-Host "Your current Failover Level is: $CurrentFailoverLevel VMHosts"
Write-Host "You should have room for another $available vms, while maintaining a failover level of" $Cluster.HAFailoverLevel
Write-Host ""