I see dated threads on LQ about Deepfreeze, like this one, this one, this one, and even this tutorial.

I've also taken a look Ofris.

I'm trying to track down a product or a project that actually functions like Faronics Deepfreeze. Something that is The issue I have with most suggestions I've seen on how to get Deepfreeze-like functionality -- including Ofris -- is that file read/write redirects are manually configured to happen in userland, whether it's via an rsync backup/restore, a dd backup/restore, or configuring certain mountpoints in fstab to use a tmpfs filesystem.

I'm looking for a kernel level driver that intercepts all read/writes and redirects to a temp space.

At one point in time, it seems like Faronics even offered a Linux version of Deepfreeze, but I can't seem to find that version of Deepfreeze anywhere on their website.

Is anyone aware if such a product or project exists for linux?

The simplest approach would be to install on an lvm and then boot a snapshot copy which uses a RAM-backed block device. That way any changes would go into RAM and be freed on shutdown, and you wouldn't have to copy the whole OS into memory. I'm not sure it would take any new code, just changes to init scripts.

Ain't going to happen. Even if overlayfs does make it upstream this time (3.18), you still have to setup the overlays.
You don't get nuthin fer nuthin.

Overlayfs has been fighting to get into the mainline for years - and aufs before that.

Snaps are useful, but you lose everything - incuding logs. May suit, or not depending on situation. Really handy after a botched update ...

I tried to dig up more information about overlayfs, but it the impression I got is that the best way to learn about it is probably by reading the source code. The wikipedia page is pretty sparse...

Any pointers to good documentation for overlayfs?

syg00, I'm not sure what you mean by "snaps". Is that LVM snapshots or something else?

Sounds like this might be the way to go, especially if syg00 is talking about LVM snapshots. I'm a little rusty with LVM, but I get the general concepts and remember most of the major commands. Could you point me in the right direction where I an learn more about how to boot an LVM snapshot into a RAM-backed block device?

Yes I was referring to snapshots - btrfs in my case, but conceptually similar to LVM.

There isn't much doco about overlayfs as it hasn't made it to the mainline kernel (yet). Ubuntu seem to have done a bit to make it available to their users - there is also overlayroot, a package (primarily) for Ubuntu.
Seems overlayfs may be in rawhide soon if you use Fedora.