Re: [Qemu-devel] [RFC] Disk integrity in QEMU

[Anthony Liguori]

Dor Laor wrote:
> Avi Kivity wrote:
>
> Since there is ongoing effort (both by IT and developers) to keep the 
> base images as big as possible, it guarantees that
> this data is best suited for caching in the host while the private 
> leaf images will be uncached.

A proper CAS solution is really such a better approach.  qcow2 
deduplification is an interesting concept, but such a hack :-)

> This way we provide good performance and caching for the shared parent 
> images while also promising correctness.

You get correctness by using O_DSYNC.  cache=off should disable the use 
of the page cache everywhere.

Regards,

Anthony Liguori

> Actually this is what happens on mainline qemu with cache=off.
>
> Cheers,
> Dor
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