PowerShell for Windows Admins


April 29, 2013  1:17 PM

CIM vs WMI cmdlets-remote execution speed

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Following on from my previous post we’ll look at how the two types of cmdlets compare for accessing remote machines.

I used a similar format to the previous tests but was accessing a remote machine.

First off was the WMI cmdlet – using DCOM to access the remote Windows 2012 server

PS> 1..100 | foreach { Measure-Command -Expression{1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem -ComputerName W12SUS }}
} | Measure-Object -Average TotalMilliseconds

Count    : 100 Average  : 2084.122547 Sum      : Maximum  :
Minimum  : Property : TotalMilliseconds

 

The CIM cmdlets are similar but apparently a bit slower – probably due to having to build the WSMAN connection and teat it down each time.

PS> 1..100 | foreach { Measure-Command -Expression{1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -ComputerName W12SUS }} } | Measure-Object -Average TotalMilliseconds

Count    : 100 Average  : 2627.287458 Sum      : Maximum  :
Minimum  : Property : TotalMilliseconds

 

So what happens is you run the CIM command over a CIM session?

PS> $sess = New-CimSession -ComputerName W12SUS PS> 1..100 | foreach { Measure-Command -Expression{1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -CimSession $sess }} } |
Measure-Object -Average TotalMilliseconds

Count    : 100 Average  : 877.746649999999 Sum      :
Maximum  : Minimum  : Property : TotalMilliseconds

This removes the setup and tear-down of the WSMAN connection. It suggests that the actual retrieval time for the CIM cmdlets should be reduced to 1749.540808 milliseconds for 100 accesses which is faster than the WMI cmdlets

It looks like the fastest way to access WMI information is across a CIM session. Next time we’ll look at running multiple commands

April 29, 2013  12:26 PM

AD Management in a Month of Lunches– chapter 9 in MEAP

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

The MEAP for AD Management in a Month of Lunches has been updated with the release of chapter 9 on managing group policies


April 28, 2013  3:03 PM

CIM cmdlets vs WMI cmdlets–speed of execution

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

One question that came up at the summit was the comparative speed of execution of the new CIM cmdlets vs the old WMI cmdlets.  No of us knew the answer because we’d never tried measuring the speed.

I decided to perform some tests.

This first test is accessing the local machine.  In both cases the cmdlets are using COM.  WMI uses COM and CIM will use COM if a –ComputerName parameter isn’t used.

The results are as follows:

PS> 1..100 |
foreach {Measure-Command -Expression {
1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem} }
} | Measure-Object -Average TotalMilliseconds

Count    : 100
Average  : 2008.953978
Sum      :
Maximum  :
Minimum  :
Property : TotalMilliseconds

 

PS> 1..100 |
foreach {Measure-Command -Expression {
1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem} }
} | Measure-Object -Average TotalMilliseconds

Count    : 100
Average  : 2078.763174
Sum      :
Maximum  :
Minimum  :
Property : TotalMilliseconds

 

So for pure COM access the WMI cmdlets are marginally (3.4%) faster.

What if we use the ComputerName parameter?

PS> 1..100 |
foreach {
Measure-Command -Expression {
1..100 | foreach {Get-WmiObject -Class Win32_ComputerSystem -ComputerName $env:COMPUTERNAME } }
} | Measure-Object -Average TotalMilliseconds

Count    : 100
Average  : 1499.14379
Sum      :
Maximum  :
Minimum  :
Property : TotalMilliseconds

PS> 1..100 |
foreach {
Measure-Command -Expression {
1..100 | foreach {Get-CimInstance -ClassName Win32_ComputerSystem -ComputerName $env:COMPUTERNAME } }
} | Measure-Object -Average TotalMilliseconds

Count    : 100
Average  : 3892.921851
Sum      :
Maximum  :
Minimum  :
Property : TotalMilliseconds

This one surprised me – the WMI cmdlets are 2.5 times faster.  I suspect that is because the CIM cmdlet has to build and then breakdown the WSMAN connection each time.

Next time we’ll look at accessing a remote machine.


April 28, 2013  11:51 AM

Time for D-CRUD?

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

I was thinking on the plane back from the PowerShell summit about the CRUD activities. They are a concept we have inherited from the database world:

C = Create

R = Read

U = Update

D= Delete

Create, Update and Delete correspond directly to the PowerShell verbs – New,Set and Remove respectively.

The Read action corresponds to the Get verb.

Well sort of.

Get-* is used in two distinct scenarios.  Firstly we know of an object and we we want to read its properties – for example:

Get-Process -Name powershell

We are reading the information about the PowerShell process. That corresponds directly to the Read action in the CRUD paradigm.

However, we also use Get* when we want to Discover the processes that are running:

Get-Process

In which case we are Discovering the processes that are running.

I think its time to update the CRUD concept and make it DCRUD where D stands for discovery.


April 28, 2013  5:45 AM

Scripting Games 2013 have started

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

The 2013 Scripting Games kicked off during the PowerShell summit.  Event 1 is open and you can submit entries up until 23:59:59 GMT on 29 April 2013.  Voting on the entries starts at at midnight on 30 April.

You can enter and you can vote on the entries.  This is a community games run by powershell.org – all are welcome.

If you haven’t entered yet there is still plenty of time to get you entry in for event 1.  Start by reviewing the information at http://powershell.org/wp/the-scripting-games/

Enjoy and good luck


April 27, 2013  5:47 AM

PowerShell Summit–thank you

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

I’d like to extend a huge thank you to everyone who attended the PowerShell Summit this last week.  The Summit was a success – in no small part due to you. Your questions, and discussions, are what this is all about.

It was a pleasure meeting you all and I hope to return next year – I hope to see many of you there as well.


April 13, 2013  11:23 AM

PowerShell Deep Dives–another MEAP release

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

 

Manning have released another set of chapters in their early access program for PowerShell Deep Dives.

If you have an interest in PowerShell I would strongly urge you to buy a copy. It has chapters from a number of well known PowerShell authors together with some very good material from new authors.  Best of all the royalties are going to charity.


April 13, 2013  11:18 AM

Busy, busy, busy

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

A very busy time coming up in PowerShell land with the first PowerShell Summit kicking off in just over a week’s time.  The 2013 Scripting Games will also be starting very soon.

I’ll try and post about both of them as time allows


April 12, 2013  12:41 PM

Creating a new disk

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

I really like Windows Server Core. The concept has come of age in Windows 2012.

I needed to add a new disk to a virtual machine  – that’s easy using the Hyper-V cmdlets. But what about formating the disk.

A module new to Windows 2012 & Windows can be used.  Its the Storage module.  I’ve not had chance, or reason, to play with this module yet. So many cmdlets so little time.

Start with viewing the disks:

PS C:\Users\richard> Get-Disk | ft -a

Number Friendly Name          OperationalStatus Total Size Partition Style
—— ————-          —————– ———- —————
0      Virtual HD ATA Device  Online                120 GB MBR
1      Microsoft Virtual Disk Offline               127 GB RAW

 

Disk 1 is the new disk so need to initialise it.

PS C:\Users\richard> Initialize-Disk -Number 1 -PartitionStyle MBR

View the disks again

PS C:\Users\richard> Get-Disk | ft -a

Number Friendly Name          OperationalStatus Total Size Partition Style
—— ————-          —————– ———- —————
0      Virtual HD ATA Device  Online                120 GB MBR
1      Microsoft Virtual Disk Online                127 GB MBR

 

Create a partition on the disk -   -useMaximimSize means use all of the disk for this partition

PS C:\Users\richard> New-Partition -DiskNumber 1 -UseMaximumSize -DriveLetter R

Now view the partitions

PS C:\Users\richard> Get-Partition | ft -a

   Disk Number: 0

PartitionNumber DriveLetter Offset         Size Type
————— ———– ——         —- —-
1                           1048576      350 MB IFS
2               C           368050176 119.66 GB IFS

   Disk Number: 1

PartitionNumber DriveLetter Offset    Size Type
————— ———– ——    —- —-
1               R           1048576 127 GB Logical

And finally format the new disk:

PS C:\Users\richard> Get-Volume | where DriveLetter -eq R | Format-Volume -FileSystem NTFS -NewFileSystemLabel Backup

Confirm
Are you sure you want to perform this action?
Warning, all data on the volume will be lost!
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "Y"): Y

You get a nice friendly warning (you could bypass using –Confirm $false) and the format happens

You could pipe the cmdlets together to do everything in one pass. Best of all – the cmdlets are WMI based.


April 11, 2013  1:51 PM

Windows Server Backup

Richard Siddaway Richard Siddaway Profile: Richard Siddaway

Windows Server 2012 has a PowerShell enabled backup utility. When you enable the feature you get a module called WindowsServerBackup.  It has the cmldets you would expect for creating and managing backups. No surprise you may say as this was avialable in Windows 2008 R2.

The difference with Windows Server 2012 is that you can do restores from PowerShell cmdlets whcih wasn’t available in the earlier version.

The restore cmdlets are

Start-WBFileRecovery

Start-WBHyperVRecovery

Start-WBSystemStateRecovery

Start-WBVolumeRecovery

 

This might not replace your currebt backup system but is very useful for backing up test environments and experimenting with things like authorative AD restores.


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