Xen for Human Beings

Erast Benson erast at gnusolaris.org
Wed Apr 26 23:38:51 BST 2006

On Thu, 2006-04-27 at 07:59 +1000, Matthew Palmer wrote:
> On Wed, Apr 26, 2006 at 11:59:46AM -0700, Erast Benson wrote:
> > > On 4/26/06, Erast Benson <erast at gnusolaris.org> wrote:
> > >
> > >> ... and Linux-based distributions
> > >> with minimal performance loss (5-10%), which is way more efficient than
> > >> Xen/VMware/etc..
> > >
> > >
> > > vmware and xen don't use the same techniques, and vmware's performance
> > > overhead is considerably higher:
> > > http://en.wikipedia.org/wiki/Xen_(virtual_machine_monitor)#Comparison_with_other_Virtual_Machine_Managers_.28VMMs.29
> > 
> > Correct. Xen != UML != VMware != BrandZ
> > 
> > I tried them all and I would sort them in this way (top - best performance):
> > 
> > BrandZ
> > Xen
> What is the quantitative difference in performance between these two?  What
> number is large enough for you to rate BrandZ as "way more efficient"?

It runs with 0% overhead. Means *significantly* faster. Name your
number... 2x, 5x, 10x times faster will work too! :-)

Here is some more elaboration from the Solaris 10 Zone FAQ[1]:

"""What's the Relationship between Xen and Zones?

Some people think of Xen and Zones as competing alternatives, when in
reality they are used in a complementary fashion. That's because the two
technologies operate at different levels in the software stack. Xen
virtualizes the hardware, which allows multiple operating system kernels
to run simultaneously on (currently) one piece of physical hardware.
Solaris Zones virtualize the OS, allowing multiple operating system
environments to coexist on a single Solaris kernel. Thus the two
technologies can either be used independently or used in combination to
provide whatever set of attributes best fit the problem at hand. 

The different approaches possess efficiency, observability, sharing,
utilization, isolation and manageability attributes which can be
markedly different. The Xen approach is good for isolation, though
presents the need to manage several complete operating environments,
which can be a feature or a problem, depending on what you're trying to
do! In contrast, because of the high degree of resource sharing that is
possible, Zones are good for utilization, observability, and
manageability. """

And now about BrandZ (which is logical extension of Zones)[2]:

""" What is the difference between BrandZ and Xen?

Xen is a technology that virtualizes an entire machine, allowing you to
run a complete operating system including the kernel. BrandZ allows you
to run just an operating system's userspace components, with a Solaris
kernel under the hood. """

Once BrandZ is out, I will try to wrap it in into the NexentaOS, so
people will have a chance to try it out in familiar Ubuntu-based

[1] http://www.opensolaris.org/os/community/xen/solaris-on-xen-faq
[2] http://www.opensolaris.org/os/community/brandz/brandz_lae_faq


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