Create New-VHD via PowerShell or GUI

How To: Create New-VHD via PowerShell or GUI and attach to existing VM

If you prefer video over written format the corresponding video for this write-up can be viewed below:

Here is all the PowerShell code required for the creation of a new VHD.  The code below can be used to prompt for all needed settings to fully setup and configure a new .vhd/.vhdx and will attach it to the VM you specify.  This is a fully functional script that could be easily modified to automate a wide range of tasks involving the creation of additional .vhd(s)/.vhdx(s).  A full write-up with examples for the GUI can also be found below.

Create New-VHD with PowerShell

#----------------------Variables Used----------------------------------------
[string]$vmName = $null
[string]$vhdName = $null
[string]$vhdType = $null
[string]$path = $null
[string]$vhdPath = $null
[int64]$vhdSize = $null
[string]$dynamic = $null
[string]$confirm = $null
#--------------------END Variables Used--------------------------------------

#----------------------USER PROMPTS------------------------------------------
$vmName = Read-Host "Enter name of VM to create new VHD for"
#check to ensure VM actually exists on the local Hyp
$vms = Get-VM | Select-Object -ExpandProperty Name
if($vmName -like $vms){
    #vm was found, we can continue with questions
    $vhdName = Read-Host "Enter name of new .vhdx file (Ex VMNameDisk4)"
    $path = Read-Host "Enter path where .vhdx will reside (Ex E:\VHD\)"
    $vhdPath = $path+$vhdName+".vhdx"
    $vhdSize = Read-Host "Enter VHDSize (GB)"
    $vhdSize = [math]::round($vhdSize *1Gb, 3) #converts GB to bytes
    while("yes","no" -notcontains $dynamic){
        $dynamic = Read-Host "Will this new VHD be dynamic? (yes/no)"
    }
    if($dynamic -eq "yes"){
        $vhdType = "Dynamic"
    }
    else{
        $vhdType = "Fixed"
    }
#-------------------END USER PROMPTS------------------------------------------

    #-----------------CONFIRM CREATE NEW VHD----------------
    Write-Host "Creating new VHD:" $vhdPath "(size:" $vhdSize "),"`
        "`n VHD Type:" $vhdType `
        "`n Attaching this new VHD to:" $vmName `
             -ForegroundColor Cyan
    
    while("yes","no" -notcontains $confirm){
        $confirm = Read-Host "Proceed? (yes/no)"
    }
    #---------------END CONFIRM CREATE NEW VHD--------------
    if($confirm -eq "yes"){
        #-------------NEW VHD CREATION----------------------
        #create either a fixed or dynamic vhd depending on user choice
        try{
            if($dynamic -eq "yes"){
                New-VHD -SizeBytes $vhdSize –Path $vhdPath -Dynamic -Confirm:$false
            }
        else{
            Write-Host "Creating fixed .vhdx - this could take some time..." -ForegroundColor Cyan
            New-VHD -SizeBytes $vhdSize –Path $vhdPath -Fixed -Confirm:$false
        }
        }
        catch{
            Write-Host "There was an error creating the new VHD" -ForegroundColor Red
            Write-Error $_
        }
        #----------END NEW VHD CREATION---------------------
        #--------------ATTACH NEW VHD ----------------------
        try{

            Add-VMHardDiskDrive -VMName $vmName -Path $vhdPath
        }
        catch{
            Write-Host "There was an error attaching the new VHD to" $vmName -ForegroundColor Red
            Write-Error $_
        }
        #------------END ATTACH NEW VHD --------------------
        #now show all VHDs that are attached to the specified VM:
        Write-Host "Final Results:" -ForegroundColor Cyan
        Write-Host "--------------" -ForegroundColor Cyan
        $vm = Get-VM -Name $vmName
        Get-VHD -VMId $vm.ID | select Path
    }
    else{
        Exit
    }
}
else{
    #vm was not found
    Write-Host "The VM you specified was not located - therefore you cannot add a VHD to it" -ForegroundColor Yellow
}

Create New-VHD with GUI

1. Access VM Settings for the VM you wish to add a VHD drive for

Open Hyper-V Manager – virtmgmt.msc – right click your VM – Settings…

Hyper-V Manager – VM Settings

2. Add Hardware

Depending on your generation type being Generation 1 / Generation 2 you may see the option to add an IDE or SCSI Controller.  The example below demonstrates a Generation 2 VM selecting a SCSI Controller.

Hyper-V Manager – VM Settings – Add Hardware

3. Add Hard Drive

Hyper-V Manager – VM Settings – Add Hard Drive

4. Specify New drive to launch New Virtual Hard Disk Wizard

Hyper-V Manager – VM Settings – New Virtual Hard Disk

The first choice you will be prompted to make will be the Disk Type.  This should be chosen with great consideration.  Here is a short breakdown on disk types:

Fixed: The VHDs provision the entire disk size as it is created.  If you create a 500GB fixed VHD, it will consume 500GB of space on your storage medium regardless of how much data is actually contained within the VHD.  Fixed VHDs can take a long time to create depending on how large they will be.  These are known to perform slightly better than dynamic VHDs but that gap is closing.

Dynamic: Expanding disks that consume only as much space as is actually inside the VHD.  If you create a 500GB dynamic VHD, it will likely only be a few MB in size initially, and will grow as data is added to the VHD.

Differencing: a VHD associated with another virtual hard disk that you select when you create the differencing disk.  Used primarily to isolate changes to a virtual hard disk or the guest operating system by storing them in a separate file.

If you need additional information I suggest you check out the following articles:

Aidan Finn’s article on Choosing Between Disk Types

Technet’s article on Using differencing disks

Hyper-V Manager – VM Settings – New Virtual Hard Disk Wizard – Disk Type

Choose a location on where you would like your new VHD to be stored:

Hyper-V Manager – VM Settings – New Virtual Hard Disk Wizard – Drive Location

Determine the size of your new VHD keeping in mind that fixed VHDs will take some time to create:

Hyper-V Manager – VM Settings – New Virtual Hard Disk Wizard – Configure Disk

Confirm all settings:

Hyper-V Manager – VM Settings – New Virtual Hard Disk Wizard – Summary