Let me disagree. I'm working on a transactional OS [1] with an immutable filesystem, it's primarily a website builder. Every request creates a new snapshot of y

Let me disagree. I'm working on a transactional OS [1] with an immutable filesystem, it's primarily a website builder. Every request creates a new snapshot of your website. It's append-only for the duration of the transaction. That's the only way to provide robust rollback and also provides version snapshots for free - but it doesn't mean snapshot's can't later be removed. My solution was to provide an undo-chain of a fixed given length. Versions older than that simply "fall off the chain" and will be picked up by GC eventually. You can also make snapshots long-lived snapshots if you want. (Of course removing a snapshot is an append-only operation :P but GC will go after non-referenced snapshots eventually.) [1] https://boomla.com/ https://boomla.com/