Re: NBD prefetch read

[Wouter Verhelst <w@uter.be>]

On Thu, Mar 22, 2018 at 10:30:55PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> hmm, from xnbd Changelog:
> Protocol changes
> ~~~~~~~~~~~~~~~~
>  * NBD_CMD_BGCOPY (value 3) has been turned into NBD_CMD_CACHE (value 5)
>    to get back in sync with the original NBD server and NBD in kernel
> 
> 
> Is there any specification for NBD_CMD_CACHE? Or only the code? On first
> sight it looks very similar with our needs.

As far as I know, there's only the code. But it's easy to ask :-)

Added Takahiro Hirofuchi (the author of xNBD) to Cc.

Takahiro, would you care to comment? The virtuozzo people would like to
implement a scheme to restore things from backup with a command that to
me sounds like it would have the same (or at least, very similar)
semantics to your NBD_CMD_CACHE command. While we could define something
for ourselves from scratch, that feels a bit like a wasted effort, and I
think it might make sense to see what you've implemented and to reuse
that then if the semantics are similar and/or compatible.

Thanks,

-- 
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