Powershell: Find largest VM disk

Sometimes you need to find the largest virtual disk. Lets say if you are sizing LUNs for datastores.

Here is a script that help you do that.

Requirement are powershell and the VMware.PowerCLI module.

Use it at your own risk.

Import-Module VMware.PowerCLI

Connect-VIServer <vCenter Name>


Function Get-LargestDisk {
  param(
    $Datastores=$null
  )
  $largest = 0

  if ($Datastores -eq $null) {
    Write-Host "Searching through all VMs."
    $vms = Get-VM
  } else {
    Write-Host "Searching through VMs on datastores: $Datastores"
    $vms = $Datastores | Get-VM
  }

  foreach ($vm in $vms) {
    $hdds = $vm | Get-HardDisk

    foreach ($hdd in $hdds) {
      $size = $hdd.CapacityGB

      if ($size -gt $largest) {
        Write-Host "Found a larger VM: $vm Size: $size GB"
        $largestVm = $vm
        $largest = [math]::Round($size)
      }
    }
  }
  Write-Host "Largest Disk: $largest GB Largest VM: $largestVm"
}

Get-LargestDisk -Datastore (Get-Datastore V7000*)