Re: [Qemu-devel] [PATCH 0/5] VMWare PVSCSI paravirtual device implementation

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Mar 15, 2012 at 9:02 AM, Dmitry Fleytman
<dmitry.fleytman@ravellosystems.com> wrote:
> Below is the implementation of VMWare PVSCSI device and
> command line parameters to configure vendor name and product name
> for SCSI storage are implemented.
> Latter is needed to make PVSCSI storage devices look exactly as
> on VMWare hypervisors.
>
> With this and VMWARE3 patches V2V migration problem for VMWare
> images should be solved relatively easy.

What is the V2V strategy?

Supporting these devices is fine if we have a way to convert guests to
use virtio.  But if the plan is to keep the guests on VMware pv
devices, then that will split the development effort on support and
optimizing I/O devices.  All the performance work going into
virtio-net (vhost-net), virtio-blk, and possibly virtio-scsi isn't
easy to duplicate for VMware pv devices.  Also, we cannot extend
VMware devices easily while retaining compatibility.

I'm for supporting these devices, but we really need another step to
move migrated guests onto virtio - otherwise users will be
disappointed with KVM's support/performance.  Can you explain a bit
how you want these devices to be used?

Stefan