Take a Snapshot Before Windows Updates on an ESXi VM and Roll Back Safely
Patch Tuesday does not have to be scary. ESXi hands you an undo button for the entire VM - here is the snapshot routine around Windows updates, and the one misunderstanding about snapshots that fills datastores.
Technical AnshuVMware ESXiSnapshots
Watch the full video - the complete Windows install on ESXi, live and step by step
On a physical PC, a bad Windows update means hours of uninstalling and hoping. In an ESXi VM it can mean one restore click - if you took a snapshot first. This page builds the habit: snapshot, patch, test, delete, and says plainly what a snapshot can and cannot protect you from.
Snapshot Manager - this VM
Before October updatesrollback pointTAKEN
Age limitdelete in 1-2 daysDISCIPLINE
Snapshot is a backupno - same datastoreMYTH
A snapshot is an undo button for a change window. Treating it as storage or as a backup is where the trouble starts.
1
Take the snapshot before you touch anything
In the ESXi client, right-click the VM - Snapshots - Take snapshot
Name it like a rollback you will understand later: Before October updates or Before SQL upgrade
For a running Windows VM, a normal snapshot is fine for patching; the memory option (capturing RAM state) is heavier and rarely needed for update insurance
Run your updates or your risky change, then test the VM properly - log in, open the application, check the services
2
Roll back in one move if it goes wrong
If the update breaks something, do not spend the day uninstalling patches one by one. Power the VM down if advised, open Snapshots, select the pre-update snapshot and choose Restore / Go to. The VM returns to the exact state it was in - files, registry, everything - in minutes. Then investigate the failed update calmly on a copy or in the next maintenance window. This is the single most confidence-giving feature ESXi gives a Windows admin: every risky change gets an undo button.
3
The honesty section - what a snapshot is not
Not a backup: the snapshot lives on the same datastore, in the same host, as the VM. Host dies, datastore dies, snapshot dies with it. Backups are copies somewhere else
Not a parking spot: while a snapshot exists, every disk write goes to a growing delta file. Leave it for weeks and the VM slows, the datastore fills, and deleting it takes a long consolidation
The discipline: snapshot, patch, test, delete the snapshot within a day or two of success. The undo button is for the change window, not for storage
Follow that rhythm and update day stops being frightening: the worst case is a five-minute rollback instead of a weekend rebuild.
Write it on the wall: a snapshot protects you from a bad change. A backup protects you from a dead machine. You need both, and neither replaces the other.
Watch the Complete Installation in the Video
Every click shown live - creating the VM, loading the driver and installing VMware Tools.
For an update insurance snapshot, a day or two after successful testing. Snapshots grow with every write, slow the VM, and a very large one takes a long time to consolidate when finally deleted. If you need weeks of retention, that is a backup job, not a snapshot.
Should the VM be on or off when I take the snapshot?
For patching, a running snapshot is normal and convenient. A powered-off (cold) snapshot is the cleanest possible state, and for major application upgrades some admins prefer it. Either beats no snapshot at all.
If I restore a snapshot, what happens to files created after it?
They are gone - restoring returns the whole VM, disks included, to the snapshot moment. That is exactly why the routine is snapshot, patch, test: restore is the emergency exit, and you copy out anything precious before using it.
This guide is based on the Technical Anshu video on installing Windows on VMware ESXi. Stuck on a step? Ask in the video comments - that is where answers come fastest.