Re: [Qemu-devel] Live migration using qcow2

[Kevin Wolf]

On Thu, Feb 21, 2013 at 12:02:18PM +0000, Dietmar Maurer wrote:
> > The problem is about cache coherency. Local files work just fine with
> > cache=writeback, but if you migrate to a different host, you get the problem
> > that the destination kernel may cache some parts of the image while the 
> > source
> > is still writing to it. When you do the actual switch to the destination 
> > host and
> > the backend doesn't take care of invalidating that cache, you might 
> > (partially)
> > read outdated data.
> 
> Isn't there a way to force a cache flush? 

Forcing the caches for a single file to be dropped? Not that I'm aware
of (or anyone else who looked into the problem before we decided to
document cache=none as a requirement).

Kevin