PowerShell for Windows Admins

July 20, 2014  11:49 AM

msmvps.com is down

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

My mirror blog on msmvps.com is down – as is the rest of the site.  It is being worked on. In the meantime transfer here

July 15, 2014  2:20 AM

PowerShell Summit Europe 2014 – – update 5

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Registration is now open. Access through Events menu at powershell.org

July 14, 2014  11:41 AM

Formatting disks – – the new way

Richard Siddaway Richard Siddaway Profile: Richard Siddaway
Windows 2012

Last time I showed how to format disks using the Win32_Volume CIM class. If you need to perform this activity on a Windows Server 2012/Windows 8 or later system you can use a couple of cmdlets from the Storage module

Get-Volume | where DriveLetter -ne ‘C’ | Format-Volume -FileSystem NTFS -Confirm:$false –WhatIf


If you’ve not looked at the Storage module before there is a lot of useful cmdlets.

July 13, 2014  9:34 AM

Formatting disks

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Saw a question on the forums about formatting all disks but the C: drive.  Assuming you ever need to do such a destructive activity you might want think about ths sort of approach

Get-CimInstance -ClassName Win32_Volume -Filter “DeviceId != ‘C:'” |
foreach {
Invoke-CimMethod -whatif -InputObject $psitem -MethodName Format -Arguments @{
ClusterSize = 4096
EnableCompression = $false
FileSystem = ‘NTFS’
QuickFormat = $true


Notice I’ve left the –whatif in for safety

More details on the Win32_Volume class at http://msdn.microsoft.com/en-us/library/aa394515%28v=vs.85%29.aspx

July 12, 2014  4:28 AM

Time to stock up your book collection?

Richard Siddaway Richard Siddaway Profile: Richard Siddaway
Active Directory, Books

Manning are offering 40% off everything – print & ebooks – www.manning.com. They have a very extensive set of PowerShell books – now would be the time to add to your collection

July 11, 2014  12:39 PM

CIM or WMI – – accessing remote machines

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

I much prefer the CIM cmdlets for accessing remote machines. The WMI cmdlets use DCOM which is firewall unfriendly and can often be unavailable of a server – cue the dreaded RPC server is unavailable error messages.

By contrast the CIM cmdlets use WSMAN.

For one off access to a remote machine use the computername parameter

Get-CimInstance -ClassName Win32_OperatingSystem -ComputerName RSSURFACEPRO2


If you want to access a machine multiple times in the session create a CIM session – analagous to a remoting session


$cs = New-CimSession -ComputerName RSSURFACEPRO2
Get-CimInstance -ClassName Win32_OperatingSystem -CimSession $cs


By default a CIM session uses WSMAN

£> $cs
Id           : 1
Name         : CimSession1
InstanceId   : 30c2b530-4ff7-448e-b68d-1f1282890e6a
ComputerName : RSSURFACEPRO2
Protocol     : WSMAN


though you can configure them to use DCOM if need be

$opt = New-CimSessionOption -Protocol DCOM
$csd = New-CimSession -ComputerName RSSURFACEPRO2 -SessionOption $opt
Get-CimInstance -ClassName Win32_OperatingSystem -CimSession $csd


When would you need to use DCOM – if you are accessing a machine with PowerShell 2 installed. The CIM cmdlets want to use WSMAN 3 and will error if you access a machine with WSMAN 2 installed however if you include a –Filter they will work


Get-CimInstance -ClassName Win32_OperatingSystem -ComputerName computer1

will fail if computer1 is running WSMAN 2 (PowerShell 2)

However, if you change the command to include a filter

Get-CimInstance -ClassName Win32_OperatingSystem -Filter “Manufacturer LIKE ‘Microsoft%'” -ComputerName computer1


Even if, as in this case, the filter doesn’t actually do anything

July 9, 2014  1:29 PM

PowerShell Summit Europe 2014 – – update 4

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Registration will open next Tuesday (15th July) – that’s less than 1 week

July 7, 2014  12:45 PM

Finding a CIM class

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

I was investigating something on my disks and started to look at the partitions:

£> Get-CimInstance -ClassName Win32_Partition
Get-CimInstance : Invalid class
At line:1 char:1
+ Get-CimInstance -ClassName Win32_Partition
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo          : MetadataError: (root\cimv2:Win32_Partition:String) [Get-CimInstance], CimException
+ FullyQualifiedErrorId : HRESULT 0x80041010,Microsoft.Management.Infrastructure.CimCmdlets.GetCimInstanceCommand

OK so my memory isn’t what it was and I got the class name wrong. How to find the correct class?

£> Get-CimClass *Partition*
NameSpace: ROOT/cimv2



I’ve truncated the display horizontally as not interested in methods & properties at this point
So the class I want is Win32_DiskPartition.

Get-CimClass is one of the biggest benefits from PowerShell 3.0

July 6, 2014  3:22 PM

CIM or WMI – – using methods

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

The CIM and WMI cmdlets both provide a way to use the methods on CIM classes namely Invoke-CimMethod and Invoke-WmiMethod. The cmdlets are very similar in operation.

$vol = Get-WmiObject -Class Win32_Volume -Filter “DriveLetter = ‘D:'”

Invoke-WmiMethod -InputObject $vol -Name Chkdsk -ArgumentList $false, $true, $true, $false, $false, $false


The argumenst list isn’t very informative – unless you know the class, read the documentation or investigate with Get-CimClass


Using the CIM cmdlets is a bit more informative as to what is going on.

$vol = Get-CimInstance -ClassName Win32_Volume -Filter “DriveLetter = ‘D:'”

Invoke-CimMethod -InputObject $vol -MethodName Chkdsk -Arguments @{FixErrors=$false; ForceDismount=$false; OkToRunAtB
ootUp = $false; RecoverBadSectors = $false; SkipFolderCycle = $true; VigorousIndexCheck = $true}


You present the arguments as a hash table – this means you can create the hash table and pass it to the method

$margs = @{
OkToRunAtBootUp = $false
RecoverBadSectors = $false
SkipFolderCycle = $true
VigorousIndexCheck = $true
Invoke-CimMethod -InputObject $vol -MethodName Chkdsk -Arguments $margs


This also means that you can create a default set of values and manipulate them in your scripts very easily


Using Invoke-CimMethod involves more typing but I think that’s worth it for the clarity. Of course if you are going to be using the methods of class a lot then I’d recommend that you create a CDXML module from the class – but that’s a whole different set of articles.

July 6, 2014  8:50 AM

Workflows 7: checkpointing workflows

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Consider this workflow

workflow chkpt1 {


foreach ($x in 1..20){



It will dump out the process information then output the numbers 1 to 20.  Not a particularly enlightening workflow but it forms  a nice basis for demonstrating checkpoints.

A checkpoint saves the state and data in the workflow. If the workflow is suspended or interrupted the work flow can be restarted from the most recent checkpoint rather than a complete restart from the beginning.


Change the workflow to give a long running activity

workflow chkpt1 {

foreach ($x in 1..1000){


Let the process data be displayed and then stop execution once the numbers start displaying – this is easiest if you use ISE. If you want to restart the workflow you have to start it right from the beginning.

Add a checkpoint to the workflow. This can be achieved in a number of ways.

Use the Checkpoint-Workflow activity to the workflow.

workflow chkpt1 {


foreach ($x in 1..1000){



or use the –PSPersist parameter

workflow chkpt1 {

Get-Process -PSPersist
foreach ($x in 1..1000){



I prefer to use Checkpoint-Workflow as it is more obvious to me when I review the workflow.


if you want to checkpoint your workflows – you have to start them as a job


chkpt1 –AsJob


Then shut down ISE

Open another PowerShell session with elevated privileges. Use Get-Job to see the suspended job.

View the data in the job

Receive-Job -Id 5 –Keep


Restart the job

Resume-Job -Id 5


Once the job finishes view the data and you’ll see the process data and the list of numbers.

Use Checkpoint-Workflow as many time as necessary to protect your data in long running workflows. A checkpoint is a good idea any time that it would be expensive to restart the whole process.

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