[Users] Horrid performance during disk I/O

[Sander Grendelman]

On Tue, Jan 14, 2014 at 10:38 PM, Blaster <Blaster at 556nato.com> wrote:
> On 1/14/2014 11:04 AM, Andrew Cathrow wrote:
>>
>> Did you compare virtio-block to virto-scsi, the former will likely
>> outperform the latter.
>
>
> No, but I have been meaning to, out of curiosity.
>
> But why do you say virto-blk will be faster than virtio-scsi?  The
> virtio-scsi wiki claims equal performance.
That's also what I read but ... this presentation:
http://www.linux-kvm.org/wiki/images/f/f9/2012-forum-virtio-blk-performance-improvement.pdf
claims
claims: "virtio-blk is about ~3 times faster than virtio-scsi in my setup" o_O
So testing is definitely a good idea.
>
> I've been trying to get some real numbers of the performance differences
> using iozone, but the numbers are all over the place, both on the HV and the
> guests, so not very meaningful.   Not an iozone expert, so still trying to
> figure out what I'm doing wrong there as well.

I've also done some (relatively simple) testing with fio.