Does anyone know how Live persistence works? I am writing an article, and I claim the following:
Live distributions use dm-snapshot to layer a read/write snapshot in RAM on top of the read-only media; a DVD, for example. Changes, therefore, are made in RAM and not persisted.
Fedora 9 introduces Live Persistence, a Live USB key that saves its state. With Live Persistence, the snapshot is a file on the USB key, rather than a snapshot in RAM. Changes, therefore, are automatically persisted to the USB key. Although accessing a USB key is slower than accessing RAM, more memory is available for other uses.
I believe this to be correct, but would like to verify. For example, it is possible that RAM is still used for the snapshot, but that the snapshot is persisted to the USB Key on shutdown, rather than using the file on the USB Key as the snapshot. Any insight is appreciated.
I sent an email to Douglas McClendon a few days ago to ask him, but he did not respond.