[CentOS] KVM Question

Sat Mar 5 04:45:17 UTC 2011
Arun Khan <knura9 at gmail.com>

On Sat, Mar 5, 2011 at 2:05 AM, William Warren
<hescominsoon at emmanuelcomputerconsulting.com> wrote:
> I'm curious exactly how KVM works.  If i see things right it's
> virtualization that's still within a full base operating system load
> correct?  How does KVM perform against VMware which uses a much smaller
> footprint?  Is KVM really a hypervisor?  I'm just trying figure out the
> basics of KVM..:)

I have not used VMWare for almost a decade so I unable to make any
comments on KVM v/s VMWare; I have used VirtualBox and Linux Kernel
Virtual Machine (LKVM).

IMO, the fundamental difference between LKVM and VB:

The LKVM is based upon "qemu" with hardware acceleration.  Look for
qemu-kvm package (or something similar).     It requires hardware
support in the motherboard and the CPU  (Intel is VT-x || AMD is SVM);
otherwise the LKVM modules will not load.   The kernel modules create
a device as shown:

$ ls -l /dev/kvm
crw-rw----+ 1 root kvm 10, 232 Mar  4 10:47 /dev/kvm

Whereas VB can work on any stock x86 hardware.   I think the same is
true for VMWare as well.

If you want to experiment with LKVM then I would suggest that you
first learn the basics through the command line utility qemu-kvm or
kvm (depending on the distro) and then graduate to the KVM management
tools.  You will also need to brush up your knowledge on the Linux
bridge utilities and tunctl.  Once you get the hang of it, you will
find it is quite simple and powerful.   I have been deploying LKVM
based appliances at client locations since 3Q/2009 - no issues with
LKVM thus far.

HTH
-- 
Arun Khan