A typical example of such an event is the question you get when you try to unmount a CD or DVD drive from a VM. Some Linux guest OS will place a lock on the CD or DVD, and vSphere will ask you if you want to bypass this lock. And your script just hangs there, waiting for you to reply

I have been looking for some time to come up with a solution for this automation “issue”. And finally I came up with a working solution

The Problem

The problem is quite simple to recreate. Execute the following code for a VM that is running a Linux guest OS, and that has an ISO mounted.

$vmName = 'MyVM'
$vm = Get-VM -Name $vmName
$cd = Get-CDDrive -VM $vm

Set-CDDrive -CD $cd -NoMedia -Confirm:$false

The following question will appear, provided you have the vSphere Client open.

My initial idea was to use asynchronous events on a Timer object to answer the question. But that didn’t work, since for the action code attached to such a Timer event to fire, the code has to pass through the .Net  framework. Which in case of such an outstanding question, it didn’t.

An alternative solution that I got working, was with a background job that is started just before the unmount is attempted.

The Script

function Set-CDDriveAndAnswer
{
<#
.SYNOPSIS  Unmounts a CD/DVD from a VM and answers an outstanding question
.DESCRIPTION The function will unmount a CD/DVD from a DVD.
  If the unmount causes a question, the function will answer the question.
.NOTES  Author:  Luc Dekens
.PARAMETER Name
  The DisplayName of the VM
.PARAMETER Server
  The vSphere Server on which the VM is located.
  The default is $global:defaultviserver
.EXAMPLE
  PS> Set-CDDriveAndAnswer -Name MyVM -Server $global:DefaultVIServer
.EXAMPLE
  PS> Get-VM | Set-CDDriveAndAnswer
#>
  [CmdletBinding()]
  param(
  [Parameter(Mandatory=$True,ValueFromPipeline=$True,ValueFromPipelinebyPropertyName=$True)]
  [string[]]$Name,
  [PSObject]$Server
  )

  Begin
  {
    $cdQuestion = {
      param($VmName,$vServer)
    
      $maxPass = 5
      $pass = 0
    
      Add-PSSnapin VMware*
      Connect-VIServer -Server $vServer.Name  -Session $vServer.SessionSecret | Out-Null
      while($pass -lt $maxPass){
        $question = Get-VM -Name $VmName | Get-VMQuestion -QuestionText "*locked the CD-ROM*"
        if($question){
          Set-VMQuestion -VMQuestion $question -Option Yes -Confirm:$false
          $pass = $maxPass + 1
        }
        $pass++
        sleep 1
       }
    }

    if(!$Server){
      $Server = $global:DefaultVIServer
    }
  }

  Process
  {
    $Name | %{
      $vm = Get-VM -Name $_
      $cd = Get-CDDrive -VM $vm
      $job = Start-Job -Name Check-CDQuestion -ScriptBlock $cdQuestion -ArgumentList $_,$Server
      Set-CDDrive -CD $cd -NoMedia -Confirm:$false -ErrorAction Stop
    }
  }
}

Annotation

Line 20: the function can accept the VM(s) from the pipeline

Line 27-45: the background job that will check if the unmount has caused a question. If yes, the background job will answer the question with “Yes“. The background job times out after 5 seconds.

Line 34: In a background job, you can reuse an open vSphere Server connection by using the SessionSecret property.

Line 36-38: The function looks for an outstanding “locked CD rom door” question for the specific VM. If such a question is found, the function will reply with “Yes”

Line 46-48: If no vSphere Server was passed on the Server parameter, the script will use the default vSphere Server connection that is to be found in $global:defaultviserver

Line 57: The actual unmount command. It will remove the mounted CD/DVD by using the NoMedia switch.

Sample Usage

The usage of the function is quite simple. You can call the function for a single VM

Set-CDDriveAndAnswer -Name LinuxBox

This will unmount the CD/DVD from the specific VM. The VM needs to be on the currently connected vSphere Server ($global:defaultviserver)

Or you can use it in a pipeline construct.

Get-VM | where{Get-CDDrive -VM $_} | Set-CDDriveAndAnswer

This will find all the VMs that have a CD/DVD mounted, and will unmount the CD/DVD

Enjoy!