The real strengths of the z platform are in I/O throughput and
virtualization.  Therefor, as a general rule of thumb, if your
workloads are heavily I/O bound or heavy on virtualization, you will
probably benefit from zLinux vs some other flavor of Linux on
commodity hardware.  If you were planning on deploying a large cluster
over mega-bit ethernet, the mainframe will get you better inter-node
throughput and less administrative fuss since you will have very few
hardware failures by comparison, and all but the most modestly priced
units have backup parts that kick in when the primary part needs
service.

As far as NUMBERS to tell you the difference between a z and, say an
alpha or an itanium (itanic, as the redhat folks call it) there are
such things but you are comparing apples and oranges.  Intels will do
some things very well and others poorly.  The mmx extensions makes
them great as desktop machines, but don't do much to improve overall
flops.  Even looking at the MIPS is highly misleading.  After all, AMD
machines with significantly slower clocks get much better performance
on many tasks than do Pentiums.  By the same token, no AMD system can
compete with a comparable P4 in the high-end multi-media niche,
specifically PC gaming.

Mainframes do several things no other computer does.  Mainframe memory
banks use hamming for CRCs to ensure that the entire memory bank is
consistent from state to state.  They can backup several instructions
and account for small errors in processing, caused by anything from
dust distorting a signal level to a sunspot or cosmic radiation.  Not
even a cray can do this.

Modern mainframes are internally cooled, meaning that a mainframe
comes with its own environmental controls, which no commodity platform
can boast.  To build a Linux cluster with comparable abilities will
also require a substantial investment in floorspace, cables, switching
power, and data center technicians to handle the volume of
maintainence issues.  This setup works fine for many people, most
notably google, but I can't help bt think that for a one-time
investment google could reduce their operating costs dramatically (I
don't necessarily encourage that, since they would inevitably downsize
a large portion  of their IT staff and I'd hate to see thousands more
losing their job in this tough economy.)

Perhaps there are others on the list who disagree, and will point to
hard numbers.  Nevertheless, my experience and training both tell me
that comparing two computers by the numbers is relatively fruitless.
Instead, you will make a much more informed decision by focusing on
the features.

Erik Johnson

On Tue, May 5, 2009 at 10:19 AM, Daniel Vila <[email protected]> wrote:
> Hello people , I wanna know if any of you was looking about howto compare
> a Zlinux under VM with another platform Linux server in order to know
> the convenience to implement or not a server. Any benchmark , or TPMC
> comparison will be useful.
>
> Tks in advance Dany
>
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