How does "deep freeze" works?

Question

as we all know there is a software called "deep freeze" which you probably know what it does.

Anyway, after some googling I noticed that kind of software(s) called sandboxing or virtualization software however, Im not quite sure since my further searches failed me.

So, here is my question:

How does deepfreeze actually works ? If it were making image of everything in computer(its called virtualization I guess) it would take so much space. If it were creating index of every file and checking them regulary, then it would make my computer "freeze".

So whats the magic ? How does it actually works ? does it realize when I download files by some way ?

Answer 1

The concept of how Deep Freeze works is very simple, but the actual implementation is a bit more complicated.

Basically Deep Freeze replaces the disk IO driver with its own that only write files to temporary locations and forbids modification of existing files by copying them (or just parts of the files) to a temporary store and modifying them there, behind the scenes.

This means that every time the system resumes, the store holding all modifications is purged and the system resumes from a previous state, called frozen state.

Answer 2

I don't know exactly how deep freeze works but I assume it works by redirecting writes to a temporary file and then deleting the file at shutdown.