Re: [Qemu-devel] [RFC V4 00/30] QCOW2 deduplication

[Troy Benjegerdes <hozer@hozed.org>]

On Wed, Jan 02, 2013 at 05:16:03PM +0100, Beno??t Canet wrote:
> This patchset is a cleanup of the previous QCOW2 deduplication rfc.
> 
> One can compile and install https://github.com/wernerd/Skein3Fish and use the
> --enable-skein-dedup configure option in order to use the faster skein HASH.
> 
> Images must be created with "-o dedup=[skein|sha256]" in order to activate the
> deduplication in the image.
> 
> Deduplication is now fast enough to be usable.

How does this code handle hash collisions, and do you have some regression
tests that purposefully create a dedup hash collision, and verify that the
'right thing' happens?

The next question is .. what's the right thing?

It's great that this almost works, but it seems rather dangerous to put
something like this into the mainline code without some regression tests.

(I'm also suspecting the regression test will be a great way to find 
flakey hardware)

--------------------------------------------------------------------------
Troy Benjegerdes                'da hozer'                 hozer@hozed.org

Somone asked my why I work on this free (http://www.fsf.org/philosophy/)
software & hardware (http://q3u.be) stuff and not get a real job.
Charles Shultz had the best answer:

"Why do musicians compose symphonies and poets write poems? They do it
because life wouldn't have any meaning for them if they didn't. That's why
I draw cartoons. It's my life." -- Charles Shultz