Coding Corner: Compacting a virtual hard disk

Today I am going to go over a basic script for compacting a virtual hard disk. This script creates a virtual hard disk object from a string that points to the virtual hard disk file (in the script this information is provided as a command line parameter). The script then executes the 'compact' method - which returns a VMTask object. We can then use this VMTask object to monitor the progress of the compaction:

'Script Begins

On Error Resume Next

'Connect to Virtual Server and check for failure
Set virtualServer = CreateObject("VirtualServer.Application")
If Err.number <> 0 Then error("Failed to connect to Virtual Server")

'Connect to virtual hard disk (provided as command line parameter) and check for failure
Set aVirtualHardDisk = virtualServer.GetHardDisk(WScript.Arguments(0))
If Err.number <> 0 Then error("Failed to connect to virtual hard disk")

'Start compaction process and check for failure
Set compactionTask = aVirtualHardDisk.Compact
If Err.number <> 0 Then error("Failed to compact virtual hard disk")

'Display task description
wscript.echo compactionTask.Description
wscript.echo

'Loop waiting for task completion - and display status
while not compactionTask.isComplete
wscript.echo "Compaction is " & compactionTask.PercentCompleted & "% complete"
WScript.Sleep 2000
wend

wscript.echo
wscript.echo "Compaction complete"

'Pause before exiting
WScript.Sleep 5000
wscript.quit

'Generic error handler
sub error(message)

   wscript.echo message
wscript.echo
wscript.echo Err.Description
WScript.Sleep 5000
wscript.quit

end sub

'Script Ends

As there are a couple of areas where you could hit a problem - I have put in some basic error handling to explain why things fail. Also - it should be noted that while this script will request that the virtual hard disk is compacted - the actual compaction is done by Virtual Server. This means that if you close the command prompt window while the script is running - Virtual Server will continue to compact the virtual hard disk in the background.

Cheers,
Ben

Comments

• Anonymous
  February 10, 2005
  Will this scripting be added to future release of Virtual PC anytime soon?
• Anonymous
  February 10, 2005
  To make this a little more user friendly, add something like this:
  
  'Check for CScript
  If Not IsCScript() Then
  Wscript.Echo Wscript.ScriptName & " must be run with CScript."
  Wscript.Quit 1
  End If
  
  
  
  '----------------------------------------+----------------------------------------
  ' IsCscript - Checks CScript vs. WScript
  '
  ' Date Name Comment
  ' ------ ------- -----------------------------------------------------------------
  ' 020507 CGL Created
  '----------------------------------------+----------------------------------------
  Function IsCScript()
  Dim objRegExp
  Set objRegExp = New RegExp
  objRegExp.IgnoreCase = true
  objRegExp.Pattern = "cscript.exe$"
  IsCScript = objRegExp.Test(WScript.FullName)
  Set objRegExp = Nothing
  End Function
• Anonymous
  February 11, 2005
  Raymond -
  
  We are aware of the customer demand for this - however I do not tend to talk about future releases on this blog.
  
  Christopher -
  
  Yes - this is a good idea, however I try to keep my scripts as short as possible when I am posting them to my blog.
  
  Cheers,
  Ben