bpruitt-goddard/Backup-VMs.ps1

## Backup-VMs.ps1
# Directions for use:
# Import this script using the Import-Module cmdlet
# On PoshCode at http://poshcode.org/5486 (modified from the original http://poshcode.org/3927)
# All output is logged to the backup directory in the $($BackupDriveLetter):\VMBackup\Backup-VMs.log file
# Use the Backup-VMs cmdlet to begin the process
#       Parameter BackupDriveLetter indicates the drive to put this backup onto. It must be mounted to the host running the script.
#       Parameter VMHost defines the host that contains the VMs you want to back up. If it's blank, then it just targets the host the script is running on
#       Parameter VMNames defines the specific VMs you wish to backup, otherwise it'll back up all of them on the target host
#       Switch parameter ShutHostDownWhenFinished will cause the specified host (and any VMs running on it) to shut down upon completion of the backup
# Example:
# PS> Import-Module D:\Backup-VMs.ps1
# PS> Backup-VMs -BackupDriveLetter F -VMHost HyperVHost -VMNames mydevmachine,broker77

# ----------------------------------------------------------------------------
# Note that this script requires administrator privileges for proper execution
# ----------------------------------------------------------------------------

# Note that this script requires the following:
#
# PowerShell Management Library for Hyper-V (for the Get-VM and Export-VM cmdlets)
# This installs itself wherever you downloaded it - make sure the Hyper-V folder finds its way to somewhere in $env:PSModulePath
# http://technet.microsoft.com/en-us/library/hh848559.aspx
#
# .Net 4.5 (for the CreateFromDirectory zip method)

# our one global variable is for logging
$Logfile = ""

Function Backup-VMs
{
    [CmdletBinding(SupportsShouldProcess=$True)]
    Param(
        [parameter(Mandatory = $true)]
        [string]$BackupDriveLetter,                     # $BackupDriveLetter:\VMBackups\$backupDate

        [ValidateNotNullOrEmpty()]
        [string]$VMHost,                                        # the host that holds the vms we wish to back up, otherwise the one running the script
        [string[]]$VMNames,                                     # if not specified, back up all of them
        [switch]$ShutHostDownWhenFinished       # when set, shuts down the target host, including any vms on it
        )
    process
    {
        # first, run a bunch of checks

        # check if the .Net 4.5 is installed
        $isDotNet45Installed = Test-Net45
        if (!$isDotNet45Installed)
        {
            Write-Host -ForegroundColor Red ".Net 4.5 is not installed - terminating backup script."
            Break
        }
        # check if the HyperV module is loaded
        $isHyperVModuleLoaded = Get-Module -Name Hyper-V
        if (!$isHyperVModuleLoaded)
        {
            Write-Host "Attempting to load Hyper-V module..."
            Import-Module -Name Hyper-V
            $isHyperVModuleLoaded = Get-Module -Name Hyper-V
            if (!$isHyperVModuleLoaded)
            {
                Write-Host -ForegroundColor Red "Cannot load Hyper-V module - terminating backup script."
                Break
            }
        }
        # sanitize user input (F: will become F)
        if ($BackupDriveLetter -like "*:")
        {
            $BackupDriveLetter = $BackupDriveLetter -replace ".$"
        }
        # check to make sure the user specified a valid backup location
        if ((Test-Path "$($BackupDriveLetter):") -eq $false)
        {
            Write-Host -ForegroundColor Red "Drive $($BackupDriveLetter): does not exist - terminating backup script."
            Break
        }
        # if host was not speicified, use the host running the script
        if ($VMHost -eq "")
        {
            $VMHost = Hostname
        }
        # check to make sure the specified host is a vmhost
        if (!(Get-VMHost) -icontains $VMHost)
        {
            Write-Host -ForegroundColor Red "Host $($VMHost) is not listed in Get-VMHost - terminating backup script."
            Break
        }
        # check to make sure the specified host has any vms to back up
        if (!(Get-VM -ComputerName $VMHost))
        {
            Write-Host -ForegroundColor Red "Host $($VMHost) does not appear to have any VMs running on it according to 'Get-VM -ComputerName $($VMHost)'."
            Write-Host -ForegroundColor Yellow "This can be occur if PowerShell is not running with elevated privileges."
            Write-Host -ForegroundColor Yellow "Please make sure that you are running PowerShell with Administrator privileges and try again."
            Write-Host -ForegroundColor Red "Terminating backup script."
            Break
        }
        #endregion

        #region directory business
        # make our parent directory if needed
        if ((Test-Path "$($BackupDriveLetter):\VMBackup") -eq $false)
        {
            $parentDir = New-Item -Path "$($BackupDriveLetter):\VMBackup" -ItemType "directory"
            if ((Test-Path $parentDir) -eq $false)
            {
                Write-Host -ForegroundColor Red "Problem creating $parentDir - terminating backup script."
                Break
            }
        }

        # initialize our logfile
        $Logfile = "$($BackupDriveLetter):\VMBackup\Backup-VMs.log"
        if ((Test-Path $Logfile) -eq $false)
        {
            $newFile = New-Item -Path $Logfile -ItemType "file"
            if ((Test-Path $Logfile) -eq $false)
            {
                Write-Host -ForegroundColor Red "Problem creating $Logfile - terminating backup script."
                Break
            }
        }

        $backupDate = Get-Date -Format "yyyy-MM-dd"
        $destDir = "$($BackupDriveLetter):\VMBackup\$backupDate-$VMHost-backup\"

        # make our backup directory if needed
        if ((Test-Path $destDir) -eq $false)
        {
            $childDir = New-Item -Path $destDir -ItemType "directory"
            if ((Test-Path $childDir) -eq $false)
            {
                Write-Host -ForegroundColor Red "Problem creating $childDir - terminating backup script."
                Break
            }
        }
        #endregion

        Add-content -LiteralPath $Logfile -value "==================================================================================================="
        Add-content -LiteralPath $Logfile -value "==================================================================================================="
        # now that our checks are done, start backing up
        T -text "Starting Hyper-V virtual machine backup for host $VMHost at:"
        $dateTimeStart = date
        T -text "$($dateTimeStart)"
        T -text ""

        # export the vms to the destination
        ExportMyVms -VMHost $VMHost -Destination $destDir -VMNames $VMNames

        T -text ""
        T -text "Exporting finished"

        #region compression

        # get what we just backed up
        $sourceDirectory = Get-ChildItem $destDir

        if ($sourceDirectory)
        {
            # get the total size of all of the files we just backed up
            $sourceDirSize = Get-ChildItem $destDir -Recurse | Measure-Object -property length -sum -ErrorAction SilentlyContinue
            $sourceDirSize = ($sourceDirSize.sum / 1GB)

            # get how much free space is left on our backup drive
            $hostname = Hostname
            $backupDrive = Get-WmiObject win32_logicaldisk -ComputerName $hostname | Where-Object { $_.DeviceID -eq "$($BackupDriveLetter):" }
            $backupDriveFreeSpace = ($backupDrive.FreeSpace / 1GB)

            # tell the user what we've found
            $formattedBackupDriveFreeSpace = "{0:N2}" -f $backupDriveFreeSpace
            $formattedSourceDirSize = "{0:N2}" -f $sourceDirSize
            T -text "Checking free space for compression:"
            T -text "Drive $($BackupDriveLetter): has $formattedBackupDriveFreeSpace GB free on it, this backup took $formattedSourceDirSize GB"

            # check if we need to make any room for the next backup
            $downToOne = $false
            while (!$downToOne -and $sourceDirSize > $backupDriveFreeSpace)
            {
                # clear out the oldest backup if this is the case
                $backups = Get-ChildItem -Path "$($BackupDriveLetter):\VMBackup\" -include "*-backup.zip" -recurse -name
                $backups = [array]$backups | Sort-Object

                # make sure we aren't deleting the only directory!
                if ($backups.length -gt 1)
                {
                    T -text "Removing the oldest backup [$($backups[0])] to clear up some more room"
                    Remove-Item "$($BackupDriveLetter):\VMBackup\$($backups[0])" -Recurse -Force
                    # now check again
                    $backupDrive = Get-WmiObject win32_logicaldisk -ComputerName $hostname | Where-Object { $_.DeviceID -eq "$($BackupDriveLetter):" }
                    $backupDriveFreeSpace = ($backupDrive.FreeSpace / 1GB)
                    $formattedBackupDriveFreeSpace = "{0:N2}" -f $backupDriveFreeSpace
                    T -text "Now we have $formattedBackupDriveFreeSpace GB of room"
                }
                else
                {
                    # we're down to just one backup left, don't delete it!
                    $downToOne = $true
                }
            }
            T -text "Compressing the backup..."
            # zip up everything we just did
            ZipFolder -directory $destDir -VMHost $VMHost

            $zipFileName = $destDir -replace ".$"
            $zipFileName = $zipFileName + ".zip"

            T -text "Backup [$($zipFileName)] created successfully"
            $destZipFileSize = (Get-ChildItem $zipFileName).Length / 1GB
            $formattedDestSize = "{0:N2}" -f $destZipFileSize
            T -text "Uncompressed size:`t$formattedSourceDirSize GB"
            T -text "Compressed size:  `t$formattedDestSize GB"
        }
        #endregion

        # delete the non-compressed directory, leaving just the compressed one
        Remove-Item $destDir -Recurse -Force

        T -text ""
        T -text "Finished backup of $VMHost at:"
        $dateTimeEnd = date
        T -text "$($dateTimeEnd)"
        $length = ($dateTimeEnd - $dateTimeStart).TotalMinutes
        $length = "{0:N2}" -f $length
        T -text "The operation took $length minutes"

        if ($ShutHostDownWhenFinished -eq $true)
        {
            T -text "Attempting to shut down host machine $VMHost"
            ShutdownTheHost -HostToShutDown $VMHost
        }
    }
}

## this function will shut down any vms running on the host executing this script and then shut down said host
Function ShutdownTheHost
{
    [CmdletBinding(SupportsShouldProcess=$True)]
    Param(
        [string]$HostToShutDown
        )
    process
    {
        ## Get a list of all VMs on $HostToShutDown
        $VMs = Get-VM -ComputerName $HostToShutDown
        ## only run through the list if there's anything in it
        if ($VMs)
        {
            ## For each VM on Node, Save (if necessary), Export and Restore (if necessary)
            foreach ($VM in @($VMs))
            {
                $VMName = $VM.ElementName
                $summofvm = get-vm -Name $VMName | select *
                $summhb = $summofvm.heartbeat
                $summes = $summofvm.state

                ## Shutdown the VM if HeartBeat Service responds
                if ($summhb -eq "OK")
                {
                    T -text ""
                    T -text "HeartBeat Service for $VMName is responding $summhb, saving the machine state"

                    Stop-VM -VMName $VMName -ComputerName $VMHost -Force
                }
                ## Checks to see if the VM is already stopped
                elseif (($summes -eq "Stopped") -or ($summes -eq "Suspended"))
                {
                    T -text ""
                    T -text "$VMName is $summes"
                }

                ## If the HeartBeat service is not OK, aborting this VM
                elseif ($summhb -ne "OK" -and $summes -ne "Stopped")
                {
                    T -text
                    T -text "HeartBeat Service for $VMName is responding $summhb. Aborting save state."
                }
            }
            T -text "All VMs on $HostToShutDown shut down or suspended."
        }
        T -text "Shutting down machine $HostToShutDown..."
        Stop-Computer -ComputerName $HostToShutDown
    }
}

function ZipFolder(
    [IO.DirectoryInfo] $directory)
{
    $backupFullName = $directory.FullName

    T -text ("Creating zip file for folder ($backupFullName)...")

    [IO.DirectoryInfo] $parentDir = $directory.Parent

    [string] $zipFileName

    If ($parentDir.FullName.EndsWith("\") -eq $true)
    {
        # e.g. $parentDir = "C:\"
        $zipFileName = $parentDir.FullName + $directory.Name + ".zip"
    }
    Else
    {
        $zipFileName = $parentDir.FullName + "\" + $directory.Name + ".zip"
    }

    Add-Type -Assembly System.IO.Compression.FileSystem
    $compressionLevel = [System.IO.Compression.CompressionLevel]::Optimal
    [System.IO.Compression.ZipFile]::CreateFromDirectory($directory, $zipFileName, $compressionLevel, $false)

    T -text "Successfully created zip file for folder ($backupFullName)."
}

## Check if .Net 4.5 is installed
## Taken from here http://blogs.technet.com/b/heyscriptingguy/archive/2013/11/02/powertip-find-if-computer-has-net-framework-4-5.aspx
function Test-Net45
{
    if (Test-Path 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full')
    {
        if (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full' -Name Release -ErrorAction SilentlyContinue)
        {
            return $True
        }
        return $False
    }
}

## Powershell Script to Shutdown and Export Hyper-V 2008 R2 VMs, one at a time.
## Written by Stan Czerno
## http://www.czerno.com/default.asp?inc=/html/windows/hyperv/cluster/HyperV_Export_VMs.asp
## I have modified his approach to suit our purposes
Function ExportMyVms
{
    [CmdletBinding(SupportsShouldProcess=$True)]
    Param(
        [string]$Destination,
        [string[]]$VMNames,
        [string]$VMHost
        )
    process
    {
        ## Get a list of all VMs on Node
        if ($VMNames)
        {
            if (($VMNames.Length) -gt 1)
            {
                # pass in a multiple-element string array directly
                $VMs = Get-VM -Name $VMNames -ComputerName $VMHost
            }
            else
            {
                # turn a single-element string array back into a string
                $VMNames = [string]$VMNames
                $VMs = Get-VM -Name "$VMNames" -ComputerName $VMHost
            }
        }
        else
        {
            $VMs = Get-VM -ComputerName $VMHost
        }

        ## only run through the list if there's anything in it
        if ($VMs)
        {
            foreach ($VM in @($VMs))
            {
                $listOfVmNames += $VM.Name + ", "
            }
            $listOfVmNames = $listOfVmNames -replace "..$"
            T -text "Attempting to backup the following VMs:"
            T -text "$listOfVmNames"
            T -text ""
            Write-Host "Do not cancel the export process as it may cause unpredictable VM behavior" -ForegroundColor Yellow

            ## For each VM on Node, Save (if necessary), Export and Restore (if necessary)
            foreach ($VM in @($VMs))
            {
                $VMName = $VM.Name
                $summofvm = get-vm -Name $VMName | select *
                $summhb = $summofvm.heartbeat
                $summes = $summofvm.state
                $restartWhenDone = $false

                $doexport = "no"

                ## Shutdown the VM if HeartBeat Service responds
                if (($summhb -eq "OK") -or ($summhb -like "ok*"))
                {
                    $doexport = "yes"
                    T -text ""
                    T -text "HeartBeat Service for $VMName is responding $summhb, saving the machine state"
                    $restartWhenDone = $true

                    Stop-VM -VMName $VMName -ComputerName $VMHost -Force

                    #Wait until the machine is Off
                    T -text "Waiting for shutdown operation to finish "
                    While ((Get-VM -VMName $VMName -ComputerName $VMHost).State -ne "Off")
                    {
                        Write-Host "." -NoNewLine
                        Start-Sleep -Seconds 5
                    }
                }
                ## Checks to see if the VM is already stopped
                elseif (($summes -eq "Stopped") -or ($summes -eq "Suspended") -or ($summes -eq "Off"))
                {
                    $doexport = "yes"
                    T -text ""
                    T -text "$VMName is $summes, starting export"
                }

                ## If the HeartBeat service is not OK, aborting this VM
                elseif ($summhb -ne "OK" -and $summes -ne "Stopped")
                {
                    $doexport = "no"
                    T -text ""
                    T -text "HeartBeat Service for $VMName is responding $summhb. Save state and export aborted for $VMName"
                }

                if ($doexport -eq "yes")
                {
                    $VMEnabledState = (Get-VM -VMName $VMName -ComputerName $VMHost).State
                    T -text $VMEnabledState
                    if (("Suspended", "Stopped", "Off") -contains $VMEnabledState)
                    {
                        ## If a folder already exists for the current VM, delete it.
                        if ([IO.Directory]::Exists("$($Destination)\$($VMName)"))
                        {
                            [IO.Directory]::Delete("$($Destination)\$($VMName)", $True)
                        }
                        T -text "Exporting $VMName"

                        ## Begin export of the VM
                        export-vm -Name $VMName -ComputerName $VMHost -path $Destination -ErrorAction SilentlyContinue

                        ## check to ensure the export succeeded
                        $exportedCount = (Get-ChildItem $Destination -Force -Recurse).Count

                        ## there should be way more than 5 elements in the destination - this is to account for empty folders
                        if ($exportedCount -lt 5)
                        {
                            T -text "***** Automated export failed for $VMName *****"
                            T -text "***** Manual export advised *****"
                        }

                        if ($restartWhenDone)
                        {
                            T -text "Restarting $VMName..."

                            ## Start the VM and wait for a Heartbeat with a 5 minute time-out
                            Start-VM $VMName -HeartBeatTimeOut 300 -Wait
                        }
                    }
                    else
                    {
                        T -text "Could not properly save state on VM $VMName, skipping this one and moving on."
                    }
                }
            }
        }
        else
        {
            T -text "No VMs found to back up."
        }
    }
}

## This is just a hand-made wrapper function that mimics the Tee-Object cmdlet with less fuss
## Plus, it makes our log file prettier
Function T
{
    [CmdletBinding(SupportsShouldProcess=$True)]
    Param(
        [string]$text
        )
    process
    {
        Write-Host "$text"
        $now = date
        $text = "$now`t: $text"
        Add-content -LiteralPath $Logfile -value $text
    }
}
	# Directions for use:
	# Import this script using the Import-Module cmdlet
	# On PoshCode at http://poshcode.org/5486 (modified from the original http://poshcode.org/3927)
	# All output is logged to the backup directory in the $($BackupDriveLetter):\VMBackup\Backup-VMs.log file
	# Use the Backup-VMs cmdlet to begin the process
	# Parameter BackupDriveLetter indicates the drive to put this backup onto. It must be mounted to the host running the script.
	# Parameter VMHost defines the host that contains the VMs you want to back up. If it's blank, then it just targets the host the script is running on
	# Parameter VMNames defines the specific VMs you wish to backup, otherwise it'll back up all of them on the target host
	# Switch parameter ShutHostDownWhenFinished will cause the specified host (and any VMs running on it) to shut down upon completion of the backup
	# Example:
	# PS> Import-Module D:\Backup-VMs.ps1
	# PS> Backup-VMs -BackupDriveLetter F -VMHost HyperVHost -VMNames mydevmachine,broker77

	# ----------------------------------------------------------------------------
	# Note that this script requires administrator privileges for proper execution
	# ----------------------------------------------------------------------------

	# Note that this script requires the following:
	#
	# PowerShell Management Library for Hyper-V (for the Get-VM and Export-VM cmdlets)
	# This installs itself wherever you downloaded it - make sure the Hyper-V folder finds its way to somewhere in $env:PSModulePath
	# http://technet.microsoft.com/en-us/library/hh848559.aspx
	#
	# .Net 4.5 (for the CreateFromDirectory zip method)

	# our one global variable is for logging
	$Logfile = ""

	Function Backup-VMs
	{
	[CmdletBinding(SupportsShouldProcess=$True)]
	Param(
	[parameter(Mandatory = $true)]
	[string]$BackupDriveLetter, # $BackupDriveLetter:\VMBackups\$backupDate

	[ValidateNotNullOrEmpty()]
	[string]$VMHost, # the host that holds the vms we wish to back up, otherwise the one running the script
	[string[]]$VMNames, # if not specified, back up all of them
	[switch]$ShutHostDownWhenFinished # when set, shuts down the target host, including any vms on it
	)
	process
	{
	# first, run a bunch of checks

	# check if the .Net 4.5 is installed
	$isDotNet45Installed = Test-Net45
	if (!$isDotNet45Installed)
	{
	Write-Host -ForegroundColor Red ".Net 4.5 is not installed - terminating backup script."
	Break
	}
	# check if the HyperV module is loaded
	$isHyperVModuleLoaded = Get-Module -Name Hyper-V
	if (!$isHyperVModuleLoaded)
	{
	Write-Host "Attempting to load Hyper-V module..."
	Import-Module -Name Hyper-V
	$isHyperVModuleLoaded = Get-Module -Name Hyper-V
	if (!$isHyperVModuleLoaded)
	{
	Write-Host -ForegroundColor Red "Cannot load Hyper-V module - terminating backup script."
	Break
	}
	}
	# sanitize user input (F: will become F)
	if ($BackupDriveLetter -like "*:")
	{
	$BackupDriveLetter = $BackupDriveLetter -replace ".$"
	}
	# check to make sure the user specified a valid backup location
	if ((Test-Path "$($BackupDriveLetter):") -eq $false)
	{
	Write-Host -ForegroundColor Red "Drive $($BackupDriveLetter): does not exist - terminating backup script."
	Break
	}
	# if host was not speicified, use the host running the script
	if ($VMHost -eq "")
	{
	$VMHost = Hostname
	}
	# check to make sure the specified host is a vmhost
	if (!(Get-VMHost) -icontains $VMHost)
	{
	Write-Host -ForegroundColor Red "Host $($VMHost) is not listed in Get-VMHost - terminating backup script."
	Break
	}
	# check to make sure the specified host has any vms to back up
	if (!(Get-VM -ComputerName $VMHost))
	{
	Write-Host -ForegroundColor Red "Host $($VMHost) does not appear to have any VMs running on it according to 'Get-VM -ComputerName $($VMHost)'."
	Write-Host -ForegroundColor Yellow "This can be occur if PowerShell is not running with elevated privileges."
	Write-Host -ForegroundColor Yellow "Please make sure that you are running PowerShell with Administrator privileges and try again."
	Write-Host -ForegroundColor Red "Terminating backup script."
	Break
	}
	#endregion

	#region directory business
	# make our parent directory if needed
	if ((Test-Path "$($BackupDriveLetter):\VMBackup") -eq $false)
	{
	$parentDir = New-Item -Path "$($BackupDriveLetter):\VMBackup" -ItemType "directory"
	if ((Test-Path $parentDir) -eq $false)
	{
	Write-Host -ForegroundColor Red "Problem creating $parentDir - terminating backup script."
	Break
	}
	}

	# initialize our logfile
	$Logfile = "$($BackupDriveLetter):\VMBackup\Backup-VMs.log"
	if ((Test-Path $Logfile) -eq $false)
	{
	$newFile = New-Item -Path $Logfile -ItemType "file"
	if ((Test-Path $Logfile) -eq $false)
	{
	Write-Host -ForegroundColor Red "Problem creating $Logfile - terminating backup script."
	Break
	}
	}

	$backupDate = Get-Date -Format "yyyy-MM-dd"
	$destDir = "$($BackupDriveLetter):\VMBackup\$backupDate-$VMHost-backup\"

	# make our backup directory if needed
	if ((Test-Path $destDir) -eq $false)
	{
	$childDir = New-Item -Path $destDir -ItemType "directory"
	if ((Test-Path $childDir) -eq $false)
	{
	Write-Host -ForegroundColor Red "Problem creating $childDir - terminating backup script."
	Break
	}
	}
	#endregion

	Add-content -LiteralPath $Logfile -value "==================================================================================================="
	Add-content -LiteralPath $Logfile -value "==================================================================================================="
	# now that our checks are done, start backing up
	T -text "Starting Hyper-V virtual machine backup for host $VMHost at:"
	$dateTimeStart = date
	T -text "$($dateTimeStart)"
	T -text ""

	# export the vms to the destination
	ExportMyVms -VMHost $VMHost -Destination $destDir -VMNames $VMNames

	T -text ""
	T -text "Exporting finished"

	#region compression

	# get what we just backed up
	$sourceDirectory = Get-ChildItem $destDir

	if ($sourceDirectory)
	{
	# get the total size of all of the files we just backed up
	$sourceDirSize = Get-ChildItem $destDir -Recurse \| Measure-Object -property length -sum -ErrorAction SilentlyContinue
	$sourceDirSize = ($sourceDirSize.sum / 1GB)

	# get how much free space is left on our backup drive
	$hostname = Hostname
	$backupDrive = Get-WmiObject win32_logicaldisk -ComputerName $hostname \| Where-Object { $_.DeviceID -eq "$($BackupDriveLetter):" }
	$backupDriveFreeSpace = ($backupDrive.FreeSpace / 1GB)

	# tell the user what we've found
	$formattedBackupDriveFreeSpace = "{0:N2}" -f $backupDriveFreeSpace
	$formattedSourceDirSize = "{0:N2}" -f $sourceDirSize
	T -text "Checking free space for compression:"
	T -text "Drive $($BackupDriveLetter): has $formattedBackupDriveFreeSpace GB free on it, this backup took $formattedSourceDirSize GB"

	# check if we need to make any room for the next backup
	$downToOne = $false
	while (!$downToOne -and $sourceDirSize > $backupDriveFreeSpace)
	{
	# clear out the oldest backup if this is the case
	$backups = Get-ChildItem -Path "$($BackupDriveLetter):\VMBackup\" -include "*-backup.zip" -recurse -name
	$backups = [array]$backups \| Sort-Object

	# make sure we aren't deleting the only directory!
	if ($backups.length -gt 1)
	{
	T -text "Removing the oldest backup [$($backups[0])] to clear up some more room"
	Remove-Item "$($BackupDriveLetter):\VMBackup\$($backups[0])" -Recurse -Force
	# now check again
	$backupDrive = Get-WmiObject win32_logicaldisk -ComputerName $hostname \| Where-Object { $_.DeviceID -eq "$($BackupDriveLetter):" }
	$backupDriveFreeSpace = ($backupDrive.FreeSpace / 1GB)
	$formattedBackupDriveFreeSpace = "{0:N2}" -f $backupDriveFreeSpace
	T -text "Now we have $formattedBackupDriveFreeSpace GB of room"
	}
	else
	{
	# we're down to just one backup left, don't delete it!
	$downToOne = $true
	}
	}
	T -text "Compressing the backup..."
	# zip up everything we just did
	ZipFolder -directory $destDir -VMHost $VMHost

	$zipFileName = $destDir -replace ".$"
	$zipFileName = $zipFileName + ".zip"

	T -text "Backup [$($zipFileName)] created successfully"
	$destZipFileSize = (Get-ChildItem $zipFileName).Length / 1GB
	$formattedDestSize = "{0:N2}" -f $destZipFileSize
	T -text "Uncompressed size:`t$formattedSourceDirSize GB"
	T -text "Compressed size: `t$formattedDestSize GB"
	}
	#endregion

	# delete the non-compressed directory, leaving just the compressed one
	Remove-Item $destDir -Recurse -Force

	T -text ""
	T -text "Finished backup of $VMHost at:"
	$dateTimeEnd = date
	T -text "$($dateTimeEnd)"
	$length = ($dateTimeEnd - $dateTimeStart).TotalMinutes
	$length = "{0:N2}" -f $length
	T -text "The operation took $length minutes"

	if ($ShutHostDownWhenFinished -eq $true)
	{
	T -text "Attempting to shut down host machine $VMHost"
	ShutdownTheHost -HostToShutDown $VMHost
	}
	}
	}

	## this function will shut down any vms running on the host executing this script and then shut down said host
	Function ShutdownTheHost
	{
	[CmdletBinding(SupportsShouldProcess=$True)]
	Param(
	[string]$HostToShutDown
	)
	process
	{
	## Get a list of all VMs on $HostToShutDown
	$VMs = Get-VM -ComputerName $HostToShutDown
	## only run through the list if there's anything in it
	if ($VMs)
	{
	## For each VM on Node, Save (if necessary), Export and Restore (if necessary)
	foreach ($VM in @($VMs))
	{
	$VMName = $VM.ElementName
	$summofvm = get-vm -Name $VMName \| select *
	$summhb = $summofvm.heartbeat
	$summes = $summofvm.state

	## Shutdown the VM if HeartBeat Service responds
	if ($summhb -eq "OK")
	{
	T -text ""
	T -text "HeartBeat Service for $VMName is responding $summhb, saving the machine state"

	Stop-VM -VMName $VMName -ComputerName $VMHost -Force
	}
	## Checks to see if the VM is already stopped
	elseif (($summes -eq "Stopped") -or ($summes -eq "Suspended"))
	{
	T -text ""
	T -text "$VMName is $summes"
	}

	## If the HeartBeat service is not OK, aborting this VM
	elseif ($summhb -ne "OK" -and $summes -ne "Stopped")
	{
	T -text
	T -text "HeartBeat Service for $VMName is responding $summhb. Aborting save state."
	}
	}
	T -text "All VMs on $HostToShutDown shut down or suspended."
	}
	T -text "Shutting down machine $HostToShutDown..."
	Stop-Computer -ComputerName $HostToShutDown
	}
	}

	function ZipFolder(
	[IO.DirectoryInfo] $directory)
	{
	$backupFullName = $directory.FullName

	T -text ("Creating zip file for folder ($backupFullName)...")

	[IO.DirectoryInfo] $parentDir = $directory.Parent

	[string] $zipFileName

	If ($parentDir.FullName.EndsWith("\") -eq $true)
	{
	# e.g. $parentDir = "C:\"
	$zipFileName = $parentDir.FullName + $directory.Name + ".zip"
	}
	Else
	{
	$zipFileName = $parentDir.FullName + "\" + $directory.Name + ".zip"
	}

	Add-Type -Assembly System.IO.Compression.FileSystem
	$compressionLevel = [System.IO.Compression.CompressionLevel]::Optimal
	[System.IO.Compression.ZipFile]::CreateFromDirectory($directory, $zipFileName, $compressionLevel, $false)

	T -text "Successfully created zip file for folder ($backupFullName)."
	}

	## Check if .Net 4.5 is installed
	## Taken from here http://blogs.technet.com/b/heyscriptingguy/archive/2013/11/02/powertip-find-if-computer-has-net-framework-4-5.aspx
	function Test-Net45
	{
	if (Test-Path 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full')
	{
	if (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full' -Name Release -ErrorAction SilentlyContinue)
	{
	return $True
	}
	return $False
	}
	}

	## Powershell Script to Shutdown and Export Hyper-V 2008 R2 VMs, one at a time.
	## Written by Stan Czerno
	## http://www.czerno.com/default.asp?inc=/html/windows/hyperv/cluster/HyperV_Export_VMs.asp
	## I have modified his approach to suit our purposes
	Function ExportMyVms
	{
	[CmdletBinding(SupportsShouldProcess=$True)]
	Param(
	[string]$Destination,
	[string[]]$VMNames,
	[string]$VMHost
	)
	process
	{
	## Get a list of all VMs on Node
	if ($VMNames)
	{
	if (($VMNames.Length) -gt 1)
	{
	# pass in a multiple-element string array directly
	$VMs = Get-VM -Name $VMNames -ComputerName $VMHost
	}
	else
	{
	# turn a single-element string array back into a string
	$VMNames = [string]$VMNames
	$VMs = Get-VM -Name "$VMNames" -ComputerName $VMHost
	}
	}
	else
	{
	$VMs = Get-VM -ComputerName $VMHost
	}

	## only run through the list if there's anything in it
	if ($VMs)
	{
	foreach ($VM in @($VMs))
	{
	$listOfVmNames += $VM.Name + ", "
	}
	$listOfVmNames = $listOfVmNames -replace "..$"
	T -text "Attempting to backup the following VMs:"
	T -text "$listOfVmNames"
	T -text ""
	Write-Host "Do not cancel the export process as it may cause unpredictable VM behavior" -ForegroundColor Yellow

	## For each VM on Node, Save (if necessary), Export and Restore (if necessary)
	foreach ($VM in @($VMs))
	{
	$VMName = $VM.Name
	$summofvm = get-vm -Name $VMName \| select *
	$summhb = $summofvm.heartbeat
	$summes = $summofvm.state
	$restartWhenDone = $false

	$doexport = "no"

	## Shutdown the VM if HeartBeat Service responds
	if (($summhb -eq "OK") -or ($summhb -like "ok*"))
	{
	$doexport = "yes"
	T -text ""
	T -text "HeartBeat Service for $VMName is responding $summhb, saving the machine state"
	$restartWhenDone = $true

	Stop-VM -VMName $VMName -ComputerName $VMHost -Force

	#Wait until the machine is Off
	T -text "Waiting for shutdown operation to finish "
	While ((Get-VM -VMName $VMName -ComputerName $VMHost).State -ne "Off")
	{
	Write-Host "." -NoNewLine
	Start-Sleep -Seconds 5
	}
	}
	## Checks to see if the VM is already stopped
	elseif (($summes -eq "Stopped") -or ($summes -eq "Suspended") -or ($summes -eq "Off"))
	{
	$doexport = "yes"
	T -text ""
	T -text "$VMName is $summes, starting export"
	}

	## If the HeartBeat service is not OK, aborting this VM
	elseif ($summhb -ne "OK" -and $summes -ne "Stopped")
	{
	$doexport = "no"
	T -text ""
	T -text "HeartBeat Service for $VMName is responding $summhb. Save state and export aborted for $VMName"
	}

	if ($doexport -eq "yes")
	{
	$VMEnabledState = (Get-VM -VMName $VMName -ComputerName $VMHost).State
	T -text $VMEnabledState
	if (("Suspended", "Stopped", "Off") -contains $VMEnabledState)
	{
	## If a folder already exists for the current VM, delete it.
	if ([IO.Directory]::Exists("$($Destination)\$($VMName)"))
	{
	[IO.Directory]::Delete("$($Destination)\$($VMName)", $True)
	}
	T -text "Exporting $VMName"

	## Begin export of the VM
	export-vm -Name $VMName -ComputerName $VMHost -path $Destination -ErrorAction SilentlyContinue

	## check to ensure the export succeeded
	$exportedCount = (Get-ChildItem $Destination -Force -Recurse).Count

	## there should be way more than 5 elements in the destination - this is to account for empty folders
	if ($exportedCount -lt 5)
	{
	T -text "*** Automated export failed for $VMName ***"
	T -text "*** Manual export advised ***"
	}

	if ($restartWhenDone)
	{
	T -text "Restarting $VMName..."

	## Start the VM and wait for a Heartbeat with a 5 minute time-out
	Start-VM $VMName -HeartBeatTimeOut 300 -Wait
	}
	}
	else
	{
	T -text "Could not properly save state on VM $VMName, skipping this one and moving on."
	}
	}
	}
	}
	else
	{
	T -text "No VMs found to back up."
	}
	}
	}

	## This is just a hand-made wrapper function that mimics the Tee-Object cmdlet with less fuss
	## Plus, it makes our log file prettier
	Function T
	{
	[CmdletBinding(SupportsShouldProcess=$True)]
	Param(
	[string]$text
	)
	process
	{
	Write-Host "$text"
	$now = date
	$text = "$now`t: $text"
	Add-content -LiteralPath $Logfile -value $text
	}
	}