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Re: [Nbd] state of nbd and qemu-nbd

Hi Markus,

On Thu, Aug 20, 2015 at 04:43:26PM +0200, Markus Pargmann wrote:
> Hi,
> it seems qemu-nbd has a complete separate implementation of NBD. Does
> anyone know what the state of qemu-nbd and its differences to
> nbd-server/client is?
> I am wondering why there is a second implementation. Wouldn't it be
> better to have a single implementation with more test coverage and
> contributions?
> Would a 'libnbd' be better for other projects to use nbd?

I've been thinking about writing a libnbd in the past, and in fact did
start work on something like that a few times. However, that never
really got anywhere, mostly due to time issues.

Having said that though, NBD is a fairly simple protocol for people to
implement, and people do this regularly; I'm aware of at least the
following implementations:

- nbd-server/nbd-client (d'oh)
- xnbd
- enbd
- qemu(-nbd)
- VMWare desktop (in a way that was very similar to qemu-nbd, I was able
  to mount virtual devices using nbd-to-localhost and one of their
  tools when I had a VMWare Desktop license way back when)
- nbdkit
- a few golang implementations

While most future implementations might prefer using a libnbd, I think
it's clear that some of the above, and maybe even some future
implementations, will never use it.

So I'd rather focus on making sure that the nbd-server which I put out
to the world works really well, and to make sure the protocol is
sensible, reliable, and well-documented.

It is easy to love a country that is famous for chocolate and beer

  -- Barack Obama, speaking in Brussels, Belgium, 2014-03-26

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