[CentOS-virt] moving from Xen to KVM

Wed Mar 17 13:35:30 UTC 2010
Dennis J. <dennisml at conversis.de>

On 03/17/2010 02:15 PM, Hildebrand, Nils, 232 wrote:
> Hi,
> just two questions:
> 1. Is there anything faster than XEN-paravirtualization?
> 2. Why XEN 5?
> XEN 3 is quite stable, too.
> I have 31 DomUs up and running on a single Box - and have a strong feeling that even 60 will run flawless.
> But: All of them are Para-Virtualized.
> I have no problem with disk IO-Bottlenecks since my DomUs are not Database-Servers - so there is mostly static information in the filesystems.

The term "paravirtualization" is becoming quite dated. Even if you install 
a KVM guest without that option if you choose the virtio driver inside then 
you still end up with "paravirtualized" I/O. With the advent of things like 
nested page tables and SR-IOV the "fully virtualized=slow, 
paravirtualized=way faster" logic is no longer necessarily true at least 
not for every aspect of the system.


(Disclaimer: So far I'm running all my virtualized servers on Xen but use 
KVM exclusively at home. Eventually I plan to migrate to KVM on the servers 
too but at the moment I'm not in a hurry but that is not because i think 
KVM isn't up for the task but because there is no urgent need to do so.)