On 12/02/2013 10:46, Reindl Harald wrote:
Am 12.02.2013 11:01, schrieb Gordan Bobic:
On 12/02/2013 00:42, Reindl Harald wrote:
under real load the XEON is so much faster even
with the virualization overhead which is small
these days but still exists
Small as in un-noticeable if your VMs are largely idling. Not that small if you intend to push the hardware to it's
actual limits. On a Core2 class machine, the best hypervisors manage to do it with about a 25% performance drop.
Many do worse.
http://www.altechnative.net/2012/08/04/virtual-performance-part-1-vmware/
there is never 25% performance drop in case of CPU
this may be true for IO and even this depends heavily on the
storage, a dedicated SAN storage with 1 GB writeback cache
will outperform in most cases you local disks because finally
you invest much more money and disks in a shared spindle
and the dimension is for your whole infrastructure while
most guests are not the whole day busy, the same for CPU
You didn't read the link, did you. The testing carried out was done with
2GB of RAM left to the hypervisor (with writeback caching enabled), and
the disk I/O was minimal because the whole set was primed before the
test (and easily fits into the guest's 6GB of RAM). And 75% of bare
metal is as good as it gets.
means:
you buy much better hardware with more and faster CPU's
for a single device as you would buy for 20 machines
and most of the day one or two guests can allocate
most of the ressources on their own
Sure, but that's consolidation, assuming you have loads that tessellate
nicely. If your load is capable of saturating the bare metal, your
performance will take a substantial hit if you virtualize. If you want
to argue otherwise, describe your test methodology and results. Things
may have improved somewhat from Core 2 to Core i, I haven't re-tested on
my most recent hardware - plan to do so in a week or so.
Gordan
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