On Thu, Apr 12, 2018 at 5:42 PM Eric Blake <ebl...@redhat.com> wrote:

> On 04/12/2018 05:24 AM, Richard W.M. Jones wrote:
>
> > I don't think we have nbd-server in RHEL, and in any case wouldn't it
> > be better to use qemu-nbd?
> >
> > You just start a new qemu-nbd process instead of faffing around with
> > configuration files, kill the qemu-nbd process when you're done, and

> qemu-nbd supports qcow2 already.


> That, and qemu-nbd supports extensions such as NBD_CMD_BLOCK_STATUS and
> NBD_OPT_STRUCTURED_REPLY that nbd-server has not implemented yet; a qemu
> NBD client talking to a qemu-nbd server is thus going to be able to take
> advantage of those extensions for better performance that would not be
> possible with a qemu NBD client talking to an nbd-server instance (at
> least, not without someone implementing the new features there).  And
> this is no different from the situation where nbdkit as the server lacks
> several features; the current rhv-upload patches use a python plugin to
> nbdkit, which is implemented as serializing all requests; while using
> qemu-nbd as the server would allow parallel requests to be in flight
> simultaneously.
>

Right, qemu-nbd will be better.

The manual is not very useful - do we have examples somewhere?

We will consider this for 4.3.

Nir

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