Re: questions about production use

[Stephen Evanchik <evanchsa@clarkson.edu>]

On Fri, 2004-01-23 at 12:26, Manfred.Herrmann@zipptec.de wrote:

> The following technologies/architectures are on my research list and
> my
> stupid thoughts about the differences.
> 
> xen -> pros:
>    - near to "mainframe" architecture

<snip>

> IBM mainframe Linux ... mainframe to expensive for me :-)

Comparing Xen to an IBM zSeries mainframe is not really fair. The IBM
boxes are much more than just virtualization and resource partitioning
there's a whole support structure around these things. There's a reason
they boast 5 9's of reliability -- because it actually happens. Try that
with a single Intel machine and you'll find that it's fairly difficult
if not impossible. It's not always that easy though. 

With that said, if you directly compare a zSeries mainframe to a dual
Xeon you'll find that the dual Xeon is much more capable of handling the
workloads you are most familiar with. 

Kernel compilation times are measured in a few minutes on the Xen
guests, whereas our z800 takes on the order of 30 minutes. That's just
one example, the top end of a fully loaded z800 (or even z900/z990) is
far too expensive if you just compare performance expectations side by
side.

Our z800 can scale very well considering that it is only 1 machine.. but
for the cost of scaling it up you could have purchased a few hundred
Intel machines and done a much better job or more realistically a few
dozen to keep support costs lower.


All in all we've been very happy playing with Xen here. Our z800 is
nice, but I'm not sure that we are the right kind of people to use it
effectively. It always seems we push it outside of its designed
specification.

Stephen








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