Ken’s Virtual Realty

March 9, 2009

When is it OK to default on your VI?

Filed under: LinkedIn, Virtualization — Tags: , , — Ken Cline @ 10:40 PM

I’ve noticed something about engineers. They’re never happy with the way something is configured out of the box – there’s always a better way! Well, I have a different philosophy:

“If you don’t have a very good reason to change a default value, don’t change it!”

To me, this seems totally obvious – in most cases, the default values are there for a reason.



Reaction to “Say it isn’t so: Hyper-V and XenServer outperform ESX”

Filed under: LinkedIn, Virtualization — Tags: , — Ken Cline @ 10:38 PM

Jason Boche posted an interesting article on his blog today, and I thought I’d offer my thoughts on it.

First, here’s the article from Virtualization Review magazine that started all this furor!

My guess is that part of the difference comes from both Hyper-V & Xen requiring VT capable CPUs (i.e. the VM always runs within a VT jail) while ESX supports binary translation (BT) for some 32-bit x86 instructions. The first generation of chips that supported VT weren’t very good, and VMware’s BT would often do a better job of executing the protected instructions than the hardware assist provided by the CPU. Intel has gotten better in the hardware support for virtualization which is shown in the subject test.


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