Re: [Users] Experience with low cost NFS-Storage as VM-Storage?
On Thu, 2014-01-09 at 09:53 +0100, Sander Grendelman wrote:
On Thu, Jan 9, 2014 at 9:39 AM, Markus Stockhausen
<stockhausen(a)collogia.de> wrote:
>> Von: squadra [squadra(a)gmail.com]
>> Gesendet: Donnerstag, 9. Januar 2014 09:30
>> An: Markus Stockhausen
>> Cc: Karli Sjöberg; users(a)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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