[Libguestfs] [PATCH] v2v/v2v.ml: Use larger request size for -o rhv-upload

[Richard W.M. Jones]

On Sun, Feb 13, 2022 at 05:13:37PM +0200, Nir Soffer wrote:
> This can be done in nbdcopy by adding http-ops. The pipeline in
> rhv-upload case will be:
> 
>     nbdkit (any input) -> nbdcopy (nbd-ops/http-ops) -> imageio server
> 
> Another way is to drop nbdcopy for rhv-upload - if we provide nbd
> input, we can use imageio client to read from the nbd input and write
> to imageio server. The pipeline will be:
> 
>     nbdkit (any input) -> imageio client -> imageio server
> 
> This means that the v2v output can optionally do the copy phase,
> if it knows how to read from the nbdkit input.
> 
> Yet another way is to rewrite imageio in Go, and use libnbd async API,
> which will eliminate most of the overhead of the http requests. I started
> this work with the imageio client side. You can check what we have so
> far here:
> https://github.com/oVirt/ovirt-imageio/tree/master/ovirt-img
> 
> For the long term, I think improving nbdcopy to support additional
> input/output backends is the right way and will make it more useful
> for other purposes.

This doesn't work for virt-v2v.  We want to expose NBD pipelines so
that eventually external programs which work across multiple running
virt-v2v instances can do the copying.  This cannot work if the
external programs have to worry about special cases.

This is also a reason why I'm lukewarm about special casing nbdcopy
parameters, although in this case it's only an optimization.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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