Re: [Qemu-devel] [PATCH v1 0/2] Reporting of rotation rate for disks

[Paolo Bonzini]

On 04/10/2017 13:40, Daniel P. Berrange wrote:
> 
> There is no mechanism to report this information to virtio-blk.
> We could perhaps argue that people should use virtio-scsi instead,
> because fixing virtio-blk would require enhancement to both QEMU
> and Linux virtio-blk drivers (and other guest OS drivers too)

I think long-term virtio-blk should only be used for high-performance
scenarios where the guest SCSI layer slows down things sensibly.  So
perhaps virtio-blk should always report itself as non-rotational.

> I'm unclear if there is anything I should have done wrt the
> device migration vmstate when adding this extra field, or if it
> is safe to just expect the mgmt app to set the property correctly
> on src+dst ?

That should be enough, yes.

Paolo