[Sheepdog] [PATCH 0/5] modify the usage of snapshot and cloning
morita.kazutaka at lab.ntt.co.jp
Mon Jan 11 05:39:40 CET 2010
On Mon, Jan 11, 2010 at 6:45 AM, Chris Webb <chris at arachsys.com> wrote:
>> Using a standardized format may be better such as VCDIFF.
> >From the metadata, all you know are which blocks are identical and which
> blocks have been written to and are potentially different. You're going to
> have to read the changed blocks to send them anyway, but wouldn't doing
> VCDIFF require reading the whole image including unchanged data blocks as
> well to do the pattern matching, so losing all the disk IO advantages?
I mean how about using an existing format as the output of
`shepherd diff' instead of creating a new format. I think the
VCDIFF (RFC3284) format can be one of candidates.
Xdelta and open-vcdiff use this format.
Of course, we don't need to read the whole image.
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