[Users] openvz disk access performance

[John Drescher]

On Mon, Jan 19, 2009 at 3:23 PM, Michael H. Warfield <mhw at wittsend.com> wrote:
> On Mon, 2009-01-19 at 14:49 -0500, openvz.org at jks.tupari.net wrote:
>> According to
>> http://www.scribd.com/doc/4916478/comparison-of-open-source-virtualization-technology
>> openvz has good network performance, but bad disk access performance.  Has
>> anything changed in the 4 months since that was posted?
>
>        Wow...  Could they possibly chosen a more inconvenient format.  A slide
> show in pdf fed through flash.  That was painful.  Can't even download
> the pdf to just page through it without signing up for an account.  Man
> that sucks.
>
>        I'd like to see some independent validation of those numbers and the
> methodology.  Some things in there don't seem to pass the smell test
> (particularly wrt disk times) and I wonder how well managed things like
> file system positioning (location within a disk) and fragmentation were
> managed and controlled.  I would like to know if they ran each test from
> a controlled partition (so the location on disk didn't vary) and rebuilt
> the file system each time (to manage fragmentation).  But, even the dd
> from /dev/zero to /dev/null seems rather wonky to me.
>
>        I also find it hard to believe, just from personal experience, that Xen
> would beat OpenVZ for anything.  I've run Xen and I have OpenVZ in
> production.  I've got a couple dozen OpenVZ VM's running on a single
> platform with virtually no major load average problem (400+ processes at
> any one time) where VMware crushed the processor at less than a dozen
> and Xen couldn't even keep up with that (no HW virtualization).
>
>        They also show Xen outperforming VirtualBox (I would have loved to see
> a VMware comparison in there as well) but that is totally contrary to my
> experience both with an without HW virtualization (but I noticed they
> were using HW virt for Xen and had it disabled for VirtualBox for at
> least some of the tests...  Hmmm...).
>
>        I have first hand hands on experience with VMware, VirtualBox, Xen
> (with and without HW vt), OpenVZ, Linux-Vservers, and kvm.  Their
> results are too at odds with my experience.
>

Totally agreed with every thing you said. Including with the
difficulty of reading the virtual paper....

John