Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements

Eric,

I doubt that qemu-nbd would ever want to support the situation with more
than one client connection writing to the same image at the same time;
the implications of sorting out data consistency between multiple
writers is rather complex and not worth coding into qemu.  So I think
qemu would probably prefer to just prohibit the multiple writer
situation.

Yeah, I was thinking about a 'no multiple connection' flag.

 And while multiple readers with no writer should be fine,
I'm not even sure if multiple readers plus one writer can always be made
to appear sane (if there is no coordination between the different
connections, on an image where the writer changes AA to BA then flushes
then changes to BB, it is still feasible that a reader could see AB
(pre-flush state of the first sector, post-flush changes to the second
sector, even though the writer never flushed that particular content to
disk).

Agree

--
Alex Bligh