Compact-VHD.ps1

<#
.SYNOPSIS
Fully optimizes a Hyper-V VHD/X file.

.DESCRIPTION
Mounts the target VHD/X file as read-only, performs full optimization, and then dismounts it.

.NOTES
v1.0 January 28th, 2018
(c) 2018 Eric Siron
Source: https://www.altaro.com/hyper-v/compact-hyper-v-virtual-disks-vhdx/
#>

#requires -Module Hyper-V

[CmdletBinding()]
param(
    [Parameter(Mandatory = $true, ValueFromPipeline = $true)][String]$Path,
    [Parameter()][Microsoft.Vhd.PowerShell.VhdCompactMode]$Mode = [Microsoft.Vhd.PowerShell.VhdCompactMode]::Full
)

process {
    try {
        $Path = (Resolve-Path -Path $Path -ErrorAction Stop).Path
        if ($Path -notmatch '.a?vhdx?$') { throw }
    }
    catch {
        throw('{0} is not a valid VHDX file.' -f $Path)
    }

    Write-Host "Compact-VHD: $(([System.IO.FileInfo]$Path).Name) ..." -NoNewline
    Mount-VHD -Path $Path -ReadOnly -ErrorAction Stop
    Optimize-VHD -Path $Path -Mode $Mode -ErrorAction Continue
    Dismount-VHD -Path $Path
    Write-Host -ForegroundColor Green " Done."
}