Paul Brook wrote: > cache=none: > No host caching. Reads and writes both go directly to underlying storage. > Useful to avoid double-caching. > > cache=writethrough > Reads are cached. Writes go directly to underlying storage. Useful for > broken guests that aren't aware of drive caches.
These are misleading descriptions - because cache=none does not push writes down to powerfail-safe storage, while cache=writethrough might. > cache=always (or a more scary name like cache=lie to defend against idiots) > Reads and writes are cached. Guest flushes are ignored. Useful for dumb > guests in non-critical environments. cache=unsafe would tell it like it is. Even non-idiots could be excused for getting the wrong impression from cache=always. -- Jamie
