[Users] Experience with low cost NFS-Storage as VM-Storage?

[Karli Sjöberg]

On Thu, 2014-01-09 at 09:53 +0100, Sander Grendelman wrote:
> On Thu, Jan 9, 2014 at 9:39 AM, Markus Stockhausen
> <stockhausen at collogia.de> wrote:
> >> Von: squadra [squadra at gmail.com]
> >> Gesendet: Donnerstag, 9. Januar 2014 09:30
> >> An: Markus Stockhausen
> >> Cc: Karli Sjöberg; users at ovirt.org
> >> Betreff: Re: [Users] Experience with low cost NFS-Storage as VM-Storage?
> >>
> >> try it, i bet that you will get better latency results with proper configured iscsitarget/initiator.
> >
> > I guess you did not take time to read the hole post. The latency I speak
> > of comes ontop the NFS latency. So my setup has
> >
> > - 83us latency per I/O in the hypervisor on a NFS share
> > - 450us latency per I/O in the VM on a disk hosted on the same NFS share
> >
> > If ISCSI could reduce latency to 40us instead of 83us in our wishfulst dreams
> > the QEMU penalty hits too hard.
> 
> There are some interesting tests here:
> http://www.linux-kvm.org/page/Virtio/Block/Latency

Very interesting:
"...23% overhead compared to a host read request. This deserves closer
study so that the overhead can be reduced."

Good to know people know and are at least thinking about it:)

Seeing as it´s such a fast-paced development, have you done any
benchmarks on different distributions as well? I mean like comparing the
same test against both, say Fedora and CentOS, to see if that makes any
difference?

/K

> Results seem to depend a lot on the guest OS IO stack/drivers (I see
> you use win2k3?).
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