Re: [Qemu-devel] [Nbd] [PATCH 2/2] NBD proto: add GET_LBA_STATUS extension

[Wouter Verhelst <w@uter.be>]

On Mon, Apr 04, 2016 at 12:18:37PM +0200, Markus Pargmann wrote:
> Hi,
> 
> back from my easter vacation. A bit surprised to find 200 mails in the
> NBD mailing list ;).

I'm sure you were :-)

[...]
> > Yes. This has been discussed on the nbd-general list in the past. There
> > is also the (significant) problem of the server having maybe already
> > sent out the header before discovering there is an error, at which point
> > it can *only* drop the connection.
> 
> I am still not through all the new mails on the list, so there may be
> some more discussions about this. But I will answer here simply.
> 
> I generally like the idea of having this new kind of reply. Is this
> solving our issues where we want to "stream" data directly from a
> filedescriptor into a tcp-stream?

The eventual suggestion does, yes (as I'm sure you've found out by now).

> Does it make sense to extend this for reads with an offset?

I'm not sure what you mean by that. "reads with an offset"? Don't all our reads
have an offset?

> This way we could not only send in chunks but also order them randomly. Is
> there any use-case where it does make sense to read data not sequentially?

If you just mean "read replies with offset", then yes :-)

-- 
< ron> I mean, the main *practical* problem with C++, is there's like a dozen
       people in the world who think they really understand all of its rules,
       and pretty much all of them are just lying to themselves too.
 -- #debian-devel, OFTC, 2016-02-12