Automated Hyper-V VM snapshots with PowerShell

Table of Content

Basic information
Shutdown virtual machine
Wait until virtual machine is off
Creating the snapshot
Removing the old snapshots
Starting the virtual machine
The complete script

In this blogpost I will share a script to automate Hyper-V VM snapshots with PowerShell. My goal of this script is to properly shutdown the virtual machine and create a snapshot and maintain the configured amount of snapshots based on day’s. This way I can reduce storage and it is possible to revert to a specific snapshot if the machine has broken down.

Basic information

We need some basic information that is stored in three variables. These variables contains the Hyper-V host name, the virtual machine name listed on the host and the amount of snapshots you want to maintain based on day’s.

$VirtualMachine = "My-VM"
$HyperVHost = "HVhost.lab.local"
$SnapshotDays = 10

Note: The virtual machine name can be listed by running this Powershell command Get-VM -CompterName $HyperVHost or just check in the Hyper-V Manager.

Shutdown virtual machine

in the first section we want to make sure the virtual machine is off. This is done by the Stop-VM which initiates a proper shutdown. Before we provide the command we first check if the virtual machine is running.

# Get VM information
$VM = Get-VM -ComputerName $HyperVHost -Name $VirtualMachine
# Provide shutdown command
IF ($VM.State -ne "Off") 
{
	Write-Host (Get-Date)": Shutdown $VirtualMachine"
	Stop-VM -ComputerName $HyperVHost -Name $VirtualMachine
}

Wait until virtual machine is off

The next step is to wait until the virtual machine is off and that is done by the following loop.

# Wait until VM is off
Write-Host (Get-Date)": Waiting for $VirtualMachine to be Off"

While ((Get-VM -ComputerName $HyperVHost -Name $VirtualMachine).State -ne "Off")
{
	Write-Host "." -NoNewLine
	Start-Sleep -Seconds 5
}

Write-Host " "
Write-Host (Get-Date)": $VirtualMachine is Off"

Creating the snapshot

When the virtual machine is off the snapshot is taken. The format I used is the name of the virtual machine with the date of the taken snapshot.

Write-Host (Get-Date)": Creating snapshot of $VirtualMachine"
$DateFormat = Get-Date -Format yyyy.MM.dd
$Snapshot = $VM.Name + "-" + $DateFormat

CheckPoint-VM -ComputerName $HyperVHost -Name $VirtualMachine -Snapshotname $Snapshot 
Start-Sleep -Seconds 2

Removing the old snapshots

This is done by collecting the snapshots older then the configured day’s. After these are collected the snapshots are removed by the Remove-VMSnapshot command.

Write-Host (Get-Date)": Removing snapshots of $VirtualMachine older than $SnapshotDays"

Remove-VMSnapshot (Get-VMSnapshot -ComputerName $HyperVHost -VMName $VirtualMachine | Where-Object {$_.CreationTime -lt (Get-Date).AddDays(-$SnapshotDays)})

Starting the virtual machine

The last action is to power on the virtual machine. This is done by the Start-VM command.

Write-Host (Get-Date)": Starting $VirtualMachine"
Start-VM -ComputerName $HyperVHost -Name $VM.Name

Write-Host (Get-Date)": Backup script done"

The complete script

$VirtualMachine = "My-VM"
$HyperVHost = "HVhost.lab.local"
$SnapshotDays = 10

# Get VM information
$VM = Get-VM -ComputerName $HyperVHost -Name $VirtualMachine
# Provide shutdown command
IF ($VM.State -ne "Off") 
{
	Write-Host (Get-Date)": Shutdown $VirtualMachine"
	Stop-Computer -ComputerName $VirtualMachine -Force
}

# Wait until VM is off
Write-Host (Get-Date)": Waiting for $VirtualMachine to be Off"

While ((Get-VM -ComputerName $HyperVHost -Name $VirtualMachine).State -ne "Off")
{
	Write-Host "." -NoNewLine
	Start-Sleep -Seconds 5
}
Write-Host " "
Write-Host (Get-Date)": $VirtualMachine is in Off state"

Write-Host (Get-Date)": Creating snapshot of $VirtualMachine"
$DateFormat = Get-Date -Format yyyy.MM.dd
$Snapshot = $VM.Name + "-" + $DateFormat

CheckPoint-VM -ComputerName $HyperVHost -Name $VirtualMachine -Snapshotname $Snapshot 
Start-Sleep -Seconds 2

Write-Host (Get-Date)": Removing snapshots of $VirtualMachine older than $SnapshotDays"

Remove-VMSnapshot (Get-VMSnapshot -ComputerName $HyperVHost -VMName $VirtualMachine | Where-Object {$_.CreationTime -lt (Get-Date).AddDays(-$SnapshotDays)})

Write-Host (Get-Date)": Starting $VirtualMachine"
Start-VM -ComputerName $HyperVHost -Name $VM.Name

Write-Host (Get-Date)": Backup script done"

Create a scheduled task that will run the script at a time you want and the snapshots are going to be created. I have scheduled the task to run every night at 3.00 AM so there are no interruptions on the server during production time.

I hope this is helpful for you and if you have any questions please leave a comment below.