A Tale of Two Architects – A Review

I just finished two really great books on architecture, that really necessitate sharing with all of you. These two books were written for very different purposes and with very different voices, but I found them both to be enjoyable reads with educational content.

VDI Design Guide: A comprehensive guide to help you design VMware Horizon, based on modern standards

Johan van Amersfoort

The title doesn’t exactly roll of the tongue, but honestly that might be my biggest issue with this book…

My team has a small, but challenging VDI environment, so I placed an order the day this book was released and immediately tore into that lovely amazon box when it arrived. It’s been a running joke in the infrastructure and virtualization worlds for some time now that “this is the year of VDI!” Perhaps the fact that this prognostication hasn’t come to pass is due to the complexity to running a well functioning VDI environment. Seriously, just think about all the various components that make up a VDI environment: your core infrastructure Hypervisor/SAN/Network/Security/Compute, the client, the delivery model, nevermind what’s actually in the guest! Johan does a really great job of walking through all of these components and so much more in his first book.

The style of the book emulates the VCDX design methodology. I am not, nor ever will be, a VCDX but I found his explanation of the methods to be much more engaging than in other tomes. What I mean by this is that there are some architecture books out there that are extremely dogmatic and really are just guides towards attaining a certification. Johan on the other hand does such a nice job walking the reader through the various design and architecture phases that I’d strongly consider giving this book to any burgeoning architect, whether they cared about VDI or not.

Now don’t let me fool you, that this is all method and no meat, because that would be a tragedy. Like I mentioned at the outset, my team has some VDI challenges, and with the authors thorough and detailed dissection of all the various components of a VDI infrastructure, we had immediate technical takeaways. Johan walks through all the components that make up a VDI environment, providing his recommendations for why you may want to go in a specific direction, and just as importantly why you may not!

I’ve been told on a couple of occasions that I have a unique voice when I write. Given that, I have to say I thoroughly enjoyed Mr. van Amersfoort voice through this book. As it was pointed out during his recent visit to the Datanauts podcast reading this book was like sitting down with a colleague and chatting through a technical issue. It truly made it one of the most fun technical reads I can remember.

All in all if you’re interested in VDI or general Architecture principles, do yourself a favor and pick up Johan van Amersfoort’s first book.

You can find Johan at @vdidesignguide & @vhojan

IT Architect Series: The Journey

Melissa Palmer

I picked up this book solely because I’ve enjoyed Melissa’s blog (https://vmiss.net) for some time. In the review above, I alluded to having read some bad architecture books, so I intentionally went at this book with no expectations. I have to come right out of the gate and say that this book was one of the most interesting technology books I’ve read, in that it talked about technology very little. The subtitle for this book reads “A guidebook for anyone interested in IT architecture” and a guidebook is really what Melissa gave us.

The premise to this book is to help anyone interested in technology or a burgeoning IT practitioner understand just what an Architect is and what it takes to get to be one. I can speak for no one but myself and my observations over the past 20 or so years in IT, but it seems that many systems architects just kind of eventually land in that role. They get good in one area, and maybe good in another. After some time they end up being the smartest gal/guy in the room. This is not the book to help with that sort of an endeavor and I love it! In writing this book Melissa provides a path, that worked for her en route to VCDX, on how to take a more active approach to becoming a solution provider. A sampling of the topics covered include, “Learning New Skills”, “Infrastructure Areas of Expertise” and “Architectural Building Blocks”. The format is more about the journey rather than a prescriptive roadmap. In fact throughout the book, the reader is encouraged to take a step back and see how the information shared fits within their role and worldview.

While I really enjoyed the approach and Melissa’s voice, my knock on this read is that it could use a copy edit. If you are someone who has ever joined in on the “On Premises” debate, please approach this book knowing that there is some small amount of errata present. As a wanton comma abuser, I’m certainly not throwing stones and I hope this doesn’t stop you from picking up the book; the content contained within absolutely makes up for any grammatical oopsies.

The primary content of the book clocks in at just under 200 pages. If you already are or aspire to be an architect you are going to read technical guides that are way longer than this! Just like with her blog, Melissa’s personality carries through this book. It’s obvious that a passionate person wrote this piece, in an effort to help others, all the while maintaining a sense of self. A perfect example is when discussing assumptions towards the end of the book, Melissa creates an analogy where she uses the word ‘chicken’ ten times in a paragraph. I literally laughed out loud, to which my wife responded “Is your geek book amusing dear?” Yes, yes it is.

Many IT practitioners discount some of the “softer” skills required in a business environment. It’s in this vein where I think the book really shines. If you are someone who has a hard time communicating in either written or verbal form, you are probably going to have a hard time obtaining an architect level role. Melissa spends a significant portion of the book emphasizing what these skills actually are, why you need them and tips on how to improve them. I’m thinking about getting a couple more copies of the book for some folks who could really us some self-reflection in this area…

Obviously anyone with aspirations of reaching an architect level would benefit from picking up this guide. If I were a college professor teaching folks what it was like to work in IT and to give them a broad perspective, I’d have them read this book. As someone who’s worked in an architectural role, I learned a number of things as well, meaning even seasoned IT pros can benefit from picking this up. Reading this book over the past few days, it became obvious that Melissa cares about people and the solutions they provide, so by that token perhaps we could all benefit from the reflective approach conveyed throughout this book.

You can find Melissa at @vmiss33 & @ITArchJourney

This VM is getting long in the tooth…

Leverage Operations Manager to check the “summary|oversized metric and if the VM crosses thresholds… So long, farewell, auf Wiedersehen, good night

### Connect to vROps server
$cred=Get-Credential
Connect-OMServer -Server "Demo" -Credential $cred -AuthSource "ADdomain"

### set some things that will be used later when we do some things
$when = $(get-date).AddDays(-20)
$vkey = "Summary|Oversized"
$threshold = ".75"

foreach ($vm in $(get-vm|Select-Object -First 33)){
    ### get-stats on each VM from vROps
    $vrstat=$vm|Get-OMResource
    $avg = $vrstat|Get-OMStat -Key $vkey -from $when|Select-Object -ExpandProperty Value|Measure-Object -Average

    ### Remove VM's that surpass the threshold
    write-host $vm.name, $avg.average
    if($avg.Average -gt $threshold){
        write-host $vm.name, $avg.average
        if($vm.PowerState -eq "PoweredOn"){
            ### Confirm and WhatIf have been set to true in order to protect the innocent
            stop-vm -vm $vm -Confirm:$true -WhatIf:$true
        }
    Start-Sleep 3
    ### Confirm and WhatIf have been set to true in order to protect the innocent
    Remove-VM -vm $vm -DeletePermanently -RunAsync -Confirm:$true -WhatIf:$true
    }
}

Get-EsxCli oh my!

This post is the first detailed post coming out of my presentation Ditch the UI – vSphere Management with PowerCLI at the CT VMUG Usercon. Stay tuned for the full bakers dozen of code posts!

esxcli, oh my…

I was finishing a task the day before my presentation, at the CT VMUG usercon – Ditch the UI when I happened to come across the cmdlet Get-ESXCli. My first thought was “No. Really? This command exists and I’m just finding out about it now?” sigh…

But yes it’s true, the fine folks on the PowerCLI provided us this cmdlet some time ago, and I’m just learning about it now. Well, better late than never as they say.

Before we go any further, let’s take a minute to talk about esxcli. ESXCLI is a command line interface (duh) for ESXi systems. It’s a means to modify the VMHost systems, mostly but not entirely, as it relates to the hardware systems. It’s an early & essential, but limited, way of configuring some of the management elements for your ESXi hosts.

Now I mention it’s limitations because they are essential to our story. The first big limitation is the structure of tool. It’s structure is that of namespaces with a hierarchical tree. This means that when you want to access, oh I don’t know, VMFS information/properties/methods you had to know that VMFS exists as a sub-namespaces under the esxcli storage namespace. Not a big deal and some folks actually like the structure, although it’s never really work for me.

Of bigger concern with esxcli, is locality. What I mean is that it was difficult to manage multiple systems. Of course you had options like the vMA or vCLI, but again you’re limited with connectivity options. And it was ugly to programatically try to get around these limitations.

Needless to say I was stoked to come across get-esxcli the other day.

Get-ESXCli! Oh My!!!

I’m a tinkerer. When I see a new toy, I just want to fiddle with it. That being said, I also know from experience (good and bad) what you can do with esxcli, so my first stop on Wednesday was get-help.

Not terribly helpful… I guess we have no choice but to dive in. To start off, I saved the output of get-esxcli to a variable.

$esxcli=get-esxcli -VMHost $vmhost -V2

Now that we’ve got esxcli (see what I did there?) stored as an object, let’s see what we can do. First things first, echo it back to the screen to see what we get right out of the gate.

Ok… well, this gives me something to go off of. It looks just like the structure of esxcli. I suppose that this shouldn’t be shocking, but it certainly is reassuring that we’re treading in semi-familiar territory. So it’s probably save to start moving down the tree.

Thank you Jeffrey Snover and team for allowing us to experience the wonders of things like tab complete and accessing sub-elements via the dot operator. So looking at a the output of $esxcli.network.nic we see that we can access things like TCP Segmentation Offload and VLAN’s. We get a few direct methods against our current level of the tree in addition to a Help() method.

OK, so this is starting to make a little more sense now. We’re basically taking the same namespaces and methods, but just making them look like PowerShell. At this point I figured I was good to go and just started firing off commands… which resulted in a lot of red text. After one of my frustrating attempts I actually paid attention to what tab-complete was showing me

Hey there “Invoke”? What are you doing there? How come I haven’t seen you in these parts before? After a few tests to get the syntax down, I learned that the .Invoke() method is how we actually get work done, and I can get down to the task I’d originally been so happy to automate.

Accessing the VAAI primitive

Ok, so I wasn’t quite ready to get to work yet.

$esxcli.storage.vmfs.unmap.Help()

After checking out help, just to make sure, I was ready to go…

Here’s my first script using the get-esxcli cmdlet. My whole intent was to programmatically go through my datastores, which resided on a thin-provisioned SAN, to free up any space that needed reclamation.

### Disclaimer. This one needs work, I was just so excited to learn about this cmdlet! To be continued....
Set-PowerCLIConfiguration -WebOperationTimeoutSeconds -1 -Scope Session -Confirm:$false

foreach ($cluster in $(get-cluster)){
  $dsarray=get-cluster $cluster|get-datastore
  $vmhost=get-cluster $cluster|Get-VMHost|select -First 1
  $esxcli=get-esxcli -VMHost $vmhost -V2
  foreach ($ds in $dsarray|where{$_.Type -eq 'VMFS'}){
      $esxcli.storage.vmfs.unmap.Invoke(@{reclaimunit = 60; volumelabel =$ds.name})
  }
}

I went at this script knowing that my storage volumes were mapped to all hosts in each of my clusters. If you weren’t in a similar vanilla situation you’d have to get a bit tricksier with your selection logic. However with knowledge of my environment at hand it was pretty simple to:

line 4: Iterate through each of my clusters.
line 5: Get each datastore for the specified cluster
line 6: Get the first VMHost in the cluster. This is ok because I know that all datastores are associated with all hosts in a given cluster.
line 7: Use our new friend get-esxcli against the previously retrieved VMHost.
lines 8-10: Iterate through each datastore in the cluster and run leverage the invoke method against the VMFS UNMAP primative
$esxcli.storage.vmfs.unmap.Invoke(@{reclaimunit = 60; volumelabel =$ds.name})

With that I was able to return a not insignificant amount of freed up space back to my array. After writing PowerShell code leveraging PowerCLI for the last few years, I’m feeling like I have a new array of opportunities open to me after newly discovering the Get-ESXCli cmdlet.

Happy scripting!

Scott

 

Performance Reports via vCenter statistics

Leverage get-stat to pull statistics from vCenter, build performance report based on averages

Connect-VIServer 
$myCol = @()
$start = (Get-Date).AddDays(-30)
$finish = Get-Date

$objServers = get-cluster cluster | Get-VM
foreach ($server in $objServers) {
    if ($server.guest.osfullname -ne $NULL){
        if ($server.guest.osfullname.contains("Windows")){
            $stats = get-stat -Entity $server -Stat "cpu.usage.average","mem.usage.average" -Start $start -Finish $finish

            $ServerInfo = ""|Select vName, OS, Mem, AvgMem, MaxMem, CPU, AvgCPU, MaxCPU, pDisk, Host
            $ServerInfo.vName  = $server.name
            $ServerInfo.OS     = $server.guest.osfullname
            $ServerInfo.Host   = $server.vmhost.name
            $ServerInfo.Mem    = $server.memoryGB
            $ServerInfo.AvgMem = $("{0:N2}" -f ($stats | where {$_.MetricId -eq "mem.usage.average"} |Measure-Object -Property Value -Average ).Average)
            $ServerInfo.MaxMem = $("{0:N2}" -f ($stats | where {$_.MetricId -eq "mem.usage.average"} |Measure-Object -Property Value -Maximum ).Maximum)
            $ServerInfo.CPU    = $server.numcpu
            $ServerInfo.AvgCPU = $("{0:N2}" -f ($stats | where {$_.MetricId -eq "cpu.usage.average"} |Measure-Object -Property Value -Average ).Average)
            $ServerInfo.MaxCPU = $("{0:N2}" -f ($stats | where {$_.MetricId -eq "cpu.usage.average"} |Measure-Object -Property Value -Maximum ).Maximum)
            $ServerInfo.pDisk  =[Math]::Round($server.ProvisionedSpaceGB,2)

            $mycol+=$ServerInfo
        }
    }
}

$myCol |Sort-Object vName| export-csv "VM_report.csv" -NoTypeInformation

Install programs via Invoke-VMScript

This script is a sample from a presentation I gave at the Connecticut VMUG UserCon. You can see all of the scripts from that presentation here. CTVMUG – Ditch the UI

I first wrote about the wonder of Invoke-VMScript just about a year ago. If you were to search this blog, you’d see that it turns up quite often. Honestly if the fine folks that work on PowerCLI had stopped after Invoke-VMScript, I’d probably have been OK with that.

Cutting to the chase Invoke-VMScript allows you to run scripts within a Virtual Machine’s OS. It’s a very powerful tool in that you can run PowerShell, batch or bash scripts within the context of the VM’s Windows or Linux OS.

Why would you want to automate this amazing tool? Why wouldn’t you want to?!? By leveraging this beautiful cmdlet, you can in many cases fully automate the deployment of a VM or installation of a VM within an app. Let’s be honest, as awesome as templates are they can only take you so far. Automation tools like vRA essentially operate off the same behavior, and not everyone has the funding to get those tools. For people like me Invoke-VMScript can be an extremely powerful tool that can be leveraged to great effect.

However, with great power comes great responsibility. Because of the power presented with this tool, I’d recommend that you pay close attention to Role Based Access Control (among many other reasons). If you have a VM admin or operator with overly generous permissions, not only can they negatively impact your vSphere environment but they can also impact your VM’s as well, never mind compliance/auditing bag of worms that you can open.

OK, so we got the bad out of the way, here’s one of my favorite pieces of code I’ve ever written. It’s my favorite because it’s not pretty, but it sure gets the job done and moves the ball forward. That’s what we’re trying to do here, so here’s an example of how to leverage Invoke-VMScript to interact with VM OS.

write-host "Installing .NET Framework 4.5.2. If this step errors, you may be able to run the install script at c:\temp\.net4.5.2install.ps1"

    $installScript = @(
        'if (!$(test-path c:\temp\.NET4.5.2)) { New-Item -ItemType directory -path c:\temp\.NET4.5.2 }',
        '$NetFxURL = "http://download.microsoft.com/download/E/2/1/E21644B5-2DF2-47C2-91BD-63C560427900/NDP452-KB2901907-x86-x64-AllOS-ENU.exe"',
        '$NetFxPath = "c:\temp\.NET4.5.2\NDP452-KB2901907-x86-x64-AllOS-ENU.exe"',
        '$WebClient = New-Object System.Net.WebClient',
        '$WebClient.DownloadFile($NetFxURL,$NetFxPath)',
        '$process = (Start-Process -FilePath $NetFxPath -ArgumentList "/q /norestart" -Wait -Verb RunAs -PassThru)',
        'wuauclt /detectnow /reportnow',
        'wuauclt /updatenow'
    )

    foreach ($line in $installScript) {
        Invoke-VMScript `
			-ScriptText "echo ""$line"">>C:\temp\.net4.5.2install.ps1" `
			-ScriptType Bat `
			-vm $serverData.Hostname `
			-GuestCredential $creds.LocalAdmin
    }

    Invoke-VMScript `
		-ScriptText "echo ""$line"">>C:\temp\.net4.5.2install.ps1" `
		-ScriptType Bat `
		-vm $serverData.Hostname `
		-GuestCredential $creds.LocalAdmin
}

Please note this script could be condensed considerably by removing the backtick ` that allows us to continue a script command onto the next line, as exampled on lines 14-27

line 3-12: Store a series of commands into the array $installScript
line 14-20: Iterate through the $installScript array. For each line make use of the Install-VMScript command to echo the value out to a local file within the VM.
line 22-27: Use Invoke-VMScript to call the script that was created in the previous block.

It’s that simple. But I guess that’s the beauty of the solution. There are way more complicated ways of accomplishing the same ends. BUT if you have the tool, it’s easy and it’s free… Well I guess I’ll end this post similarly to how I started it: Why wouldn’t you make use of this amazing tool….

Checking SPBM compliance

Use New-VIProperty to save SPBM object within VirtualMachine objects.
Test to see if VM’s are compliant with their assign policy. If not, migrate to compliant storage.

### warning, highly inefficient code follows. simply an example for how to use VIproperty
New-VIProperty -Name SpbmCompliance -ObjectType VirtualMachine -Value {
$Args[0]| Get-SpbmEntityConfiguration -CheckComplianceNow
} -Force
### end of inefficient code. well, kind of...

$targetobject=get-cluster cluster|get-vm|Where-Object {$_.name -match "sql" -or $_.name -match "application" -or $_.name -match "linux"}

### Iterate through the targetobjects and check compliance status.
foreach ($vm in $targetobject){
if ($vm.SpbmCompliance.ComplianceStatus -ne "compliant"){
write-host "uh oh, $vm not compliant with $($($vm.SpbmCompliance).StoragePolicy)" -ForegroundColor Red -BackgroundColor White
### do something about nonCompliance
$tag=$($vm|Get-TagAssignment|Where-Object{$_.tag.Category -match "StorageTiers"}).Tag.Name
$destStorage=Get-SpbmCompatibleStorage -StoragePolicy $tag"Policy"|Select-Object -First 1
move-vm $vm -Datastore $destStorage
$(get-vm $vm).SpbmCompliance.ComplianceStatus
}
else{
write-host "Hooray $VM is super duper compliant!" -ForegroundColor Black -BackgroundColor Green
}
}

Tag based SPBM policy

Tags->rule->ruleset->policy

$targetobject=get-cluster NCFCU-SB-DC-cl|get-vm|Where-Object {$_.name -match "sql" -or $_.name -match "application" -or $_.name -match "linux"}


### Setup tags, rules, SPBM policy
New-TagCategory -Name "StorageTiers" -Cardinality Multiple -EntityType Datastore, VirtualMachine 

foreach ($category in @("Gold","Silver","Whatever")){
  New-Tag -Name $category"Tier" -Category "StorageTiers" 
  $rule = New-SpbmRule -AnyOfTags $(get-tag -Name $category"Tier") 
  $ruleset =New-SpbmRuleSet -Name $category"RuleSet" -AllOfRules $rule  
  New-SpbmStoragePolicy -Name $category"TierPolicy" -AnyOfRuleSets $ruleset 
  
  ###one line version
  ###New-SpbmStoragePolicy -Name $category"Policy" -RuleSet (New-SpbmRuleSet -Name $category"RuleSet" -AllOfRules @(New-SpbmRule -AnyOfTags $(new-tag -Name $category"Tier" -Category "StorageTiers")))
}


### assign tags to disks
New-TagAssignment -Tag "GoldTier" -Entity $(get-datastore ServerSL1)
New-TagAssignment -Tag "SilverTier" -Entity $(get-datastore ServerSL2)
New-TagAssignment -Tag "WhateverTier" -Entity $(get-datastore ServerSL3)


### iterate through targetobject, setting tags & policy
foreach ($vm in $targetobject){
  switch -Wildcard ($vm.name){
    '*sql*'{
        $tag="GoldTier"
    }
    '*application*'{
        $tag="SilverTier"
    }
    '*linux*'{
        $tag="WhateverTier"
    }
  }

  ### If there's a tag, assign the appropriate policy that matches tags.
  if($tag){
    New-TagAssignment -Entity $vm -Tag $tag  
    Set-SpbmEntityConfiguration -Configuration $(Get-SpbmEntityConfiguration $vm) -StoragePolicy $tag"Policy"
  }
  Clear-Variable tag
}

Cleanup snapshots

Nobody likes old or bloated VM snapshots, but we’ve all had to deal with them from time to time. If you were feeling super crotchety or perhaps confident, you could run this simple one-liner and just take out all of the snapshots in your cluster.

get-cluster cluster|get-vm|get-snapshot|remove-snapshot -whatif

First off, I left the -whatif parameter in this snip to protect the innocent. But I guess if you’re really feeling that cranky…

Chances are you don’t want to be that guy, so perhaps a kinder approach might be warranted?

Get all snapshots in the targetobject and if surpassing the specified thresholds email your lazy admin

$datethreshold=-30
$sizethreshold=10
$targetobject=get-cluster cluster|get-vm

$snaps=$targetobject|Get-Snapshot

foreach($snap in $snaps) {
  if ($snap.created -lt (get-date).adddays($datethreshold) -or $snap.SizeGB -gt $sizethreshold) {
    $source="$global:DefaultVIServer@your.org"
    $dest="LazyAdmin@your.org"
    $subject="Clean up your room!"
    $relay="relay.your.org"
    $body="
      You've got some housecleaning to do:
      VM:           $($snap.VM)
      Snap name:    $($snap.name)
      Created date: $($snap.created)
      Size (GB):    $([math]::Round($snap.SizeGB,2))
    "
    Send-MailMessage -to $dest -From $source -Subject $subject -Body $body -SmtpServer $relay 

    #if you don't care about other peoples snapshots, just uncomment the next line and boom!
    #$snap|remove-snapshot
  }
}

 

Building Blocks: PowerCLI HardDisk #2, introducing parameters and functions

Build upon the previous Build Block example and introduce defining parameters and functions

Also introduce New-VIProperty

### Define input parameter
param
(
  [string[]]$Guests,
  $DiskSize,
  [decimal[]]$DiskNumber=0,
  [string[]]$Volume=$true,
  [string[]]$RemoveSnapshot=$true
)


### Function to get server ready for disk expansion
function Set-SnapReady{
  Param(
    $Guest
  )
  if (get-snapshot -vm $Guest  -ea SilentlyContinue){
    if($RemoveSnapshot = $false){
      write-host "Cannot expand disks due to snapshots. Exiting"
      Exit
    }
    else{
        get-snapshot -VM $Guest |remove-snapshot
    }
  }
}

### Function to extend virtual disk
function Set-DiskSize{
  Param(
    $Guest,
    $DiskSize,
    [decimal[]]$DiskNumber,
    [string[]]$Volume
  )
  if($Guest.Staaatus -ne "GuestToolsRunning" ){
    Write-Host "Too bad so sad, you'll have to manually extend the OS partition. Maybe you should fix VMtools..."
    get-vm $Guest|Get-HardDisk -name "Hard disk $DiskNumber"|Set-HardDisk -CapacityGB $DiskSize -Confirm:$false
  }
  else {
    get-vm $Guest|Get-HardDisk -name "Hard disk $DiskNumber"|Set-HardDisk -CapacityGB $DiskSize -ResizeGuestPartition -Confirm:$false
  }
  Get-HardDisk -VM $Guest -name "Hard disk $DiskNumber"
}


### main loop
New-VIProperty -ObjectType InventoryItem -Name "Staaatus" -ValueFromExtensionProperty 'Guest.ToolsRunningStatus' -Force

foreach ($Guest in $Guests){
  $Guest=get-vm $Guest
  Set-SnapReady $Guest
  Set-DiskSize $Guest $DiskSize $DiskNumber $Volume
}

Building Blocks: PowerCLI HardDisk #1

This script is a sample from a presentation I gave at the Connecticut VMUG UserCon. You can see all of the scripts from that presentation here. CTVMUG – Ditch the UI

Perhaps I’ve mis-titled this post… In reality this code chunk really introduces us to the power of the PowerCLI cmdlet Invoke-VMScript. It’s probably my biggest go-to cmdlet when working with guest operating systems. This became plainly obvious to me when I searched this blog for the string. I write about it here, here, here, and here. I also talk about it here.

This building block is actually the same chunk of code that we showed at VMworld 2017.

$cred=Get-Credential 

$Guest = Get-VM -Name "Sql01"
$DiskSize = 40
$Disk = "Hard Disk 2"
$Volume = "D"

$objDisk = Get-HardDisk -VM $Guest -Name $disk
$objDisk | Set-HardDisk -CapacityGB $DiskSize -Confirm:$false
$scriptBlock = @"
    echo rescan > c:\Temp\diskpart.txt
    echo select vol $Volume >> c:\Temp\diskpart.txt
    echo extend >> c:\Temp\diskpart.txt
    diskpart.exe /s c:\Temp\diskpart.txt
"@
Invoke-VMScript -vm $Guest -ScriptText $scriptBlock -ScriptType BAT -GuestCredential $cred 

Invoke-VMScript -vm $Guest -ScriptText "Get-PSDrive -Name $volume" -ScriptType PowerShell -GuestCredential $cred

line 1: Use the Get-Credential to prompt the user to input credentials for use later in the Invoke-VMScript cmdlet. Store these as a PScredential object in $cred.
line 3-6: Set our variables.
line 8: Return the harddisk that we’ll be working with via Get-HardDisk
line 9: Set the size of the VM hard disk that was retrieved on line 8
line 10-15: Use a Here-String to set the command that will be run in the guest OS context.
line 16: Using our friend Invoke-VMScript and our Here-String, we run the $scriptBlock in the context of the VM as a batch file.
line 18: Finally in line 18 we use Invoke-VMScript to show that the OS drive has been expanded to match our defined variable.

Easy Peasy! Our next building block is going to be even more fun, as we’ll take a very similar example to start showing how we can define our own script parameters and functions! Until then, be well!