For once I feel a little out of touch after I took a bit of a break from following the news to focus on studying, and suddenly everyone is talking about immutable distributions. What are they exactly? What are the benefits and the disadvantages of immutable systems?
My understanding is “immutable” is a bit of a misnomer and avoids the “point” of using these distros.
“Layered Distros” is a better terminology, where you can imagine the OS as multiple layers, and you can swap 1 layer out for another without modifying the others and still have a functional operational machine.
Now some of those layers have to be immutable ones at runtime for this concept to work, so thats where that part of the name comes from, but thats an implicit result from the actual point/use case of these distros, not the selling point.
So you can swap versions/releases of your OS very cleanly at boot, without modifying userland, and it will continue to function just the same. This lets you do stuff at the admin level like broadly releases a version update merely by having users just reboot their machines, and next time they boot up their machine will now be running on the new OS layer, with their local “user” layer being unchanged.
They also separate concerns better than classical distros. Executable binaries & libraries are separate from configuration which is separate from data. It makes backups much simpler, makes configuring new machines easier than something like Ansible, etc.