I'm looking for a live USB Linux distribution that would offer semi-persistent functionality. What I mean by that - normally the system should work in a non-persistent mode (read-only) and no writes should be performed to the medium at all. Occasionally, after controlled updates to the system, I should be able to manually save the changes from that particular session without remastering the original image (be it by CLI, a "save button" or entry in the shutdown menu).
I used an old version of Slax (version 5, maybe 4) for that very purpose a long time ago. Unfortunately, I would need something more recent now (current Wi-Fi drivers, browsers etc.).
Most of the distributions I've encountered now either allow full persistence or none. The best I've found is selectively discarding changes per session, but still writing to the medium (unnecessary wear on the drive).
Additionally, it would be nice if the distribution would load from power on to a working desktop completely unattended, surely the faster the better (but it's not that crucial).
The most adequate solution I've found so far is a Puppy LiveUSB modified for Online Banking (you can see the interesting part in Additional Information: The Details of Completed Changes). But I would hope for some more mainstream distribution, at least in part audited by being used by a large userbase.
Do some of the more popular distributions offer this kind of functionality? Or alternatively, is there a way to tweak casper-rw to behave in that manner?