#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Hyper-V checkpoints will not merge, and the disk fills
    Fix   : Complete the merge and stop it recurring
    Source: https://jbtecwiz.com/support/srv-clu-checkpoint

    Run as     : Elevated PowerShell
    Expect     : 1-6 hours
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    There is space and the merge is stuck or has not started.

    HOW TO UNDO IT
    Back up the whole virtual machine folder before merging; a failed merge
    is not reversible without it.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 6"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Hyper-V checkpoints will not merge, and the disk fills' -ForegroundColor White
Write-Host '  Complete the merge and stop it recurring' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   1-6 hours'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'List the checkpoints, including the ones a backup product created and hid.' -Why 'Recovery checkpoints created by a backup do not appear in the Hyper-V Manager tree in older versions. Listing all types is what reveals a chain that appears empty in the console.' -Command {
    Get-VMSnapshot -VMName VM01 -SnapshotType All | Format-Table Name,SnapshotType,CreationTime,ParentSnapshotName
}

Invoke-Step -Number 2 -Do 'Remove them, which triggers the merge.' -Command {
    Get-VMSnapshot -VMName VM01 -SnapshotType All | Remove-VMSnapshot -Confirm:$false
}

Invoke-Step -Number 3 -Do 'Watch the merge progress. It runs in the background and can take hours on a large chain.' -Command {
    Get-VM VM01 | Format-List Name,Status
    Get-WinEvent -LogName 'Microsoft-Windows-Hyper-V-VMMS-Admin' -MaxEvents 20 | Format-Table TimeCreated,Id,Message -Wrap
}

Invoke-Step -Number 4 -Do 'If the merge will not start, shut the virtual machine down and it will merge offline, which is faster and more reliable.' -Command {
    Stop-VM VM01
    Get-VMSnapshot -VMName VM01 -SnapshotType All | Remove-VMSnapshot
}

Invoke-Step -Number 5 -Do 'If the chain is orphaned -- the .avhdx files exist but Hyper-V has no checkpoint for them -- reconnect them with Merge-VHD, working from the newest backwards.' -Command {
    Get-VHD 'D:\VMs\VM01\disk_ABC.avhdx' | Format-List Path,ParentPath,VhdType
    Merge-VHD -Path 'D:\VMs\VM01\disk_ABC.avhdx' -DestinationPath 'D:\VMs\VM01\disk.vhdx'
}

Invoke-Step -Number 6 -Do 'Fix the backup product''s configuration so checkpoints are removed after each job -- an accumulating chain is always a symptom of that.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'The virtual machine has a single VHDX with no parent and no checkpoints remain.' 'White'
Write-Host ''
if (-not $DryRun) {
    Get-VMSnapshot -VMName VM01 -SnapshotType All
    Get-VM VM01 | Get-VMHardDiskDrive | ForEach-Object { Get-VHD $_.Path } | Format-List Path,VhdType,ParentPath
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-clu-checkpoint' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Back up the whole virtual machine folder before merging; a failed merge is not reversible without it.' 'DarkGray'
Write-Rule