Re: [Qemu-devel] Re: [PATCH 2/2] Add flush=off parameter to -drive

[Paul Brook]

> 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.

If so, then this is a serious bug.

Paul