[virt-tools-list] kvm vs. virsh

[Dennis Jacobfeuerborn]

On 08/05/2011 06:28 PM, Jeff wrote:
> I have a rather dumb question that I think I already know the answer to, but I want to be sure.
>
> I see a lot of patches, queries, etc. posted to the various Virtualization lists that refer to using commands like "kvm" and "qemu-kvm" to do various things in KVM. I'm using Red Hat Enterprise Linux, and I have installed all the qemu packages, yet I don't have those commands. I am using "virsh" to manipulate libvirt.
>
> The question is...what is the difference between the sets of commands and should I be concerned if I don't have the former set?

virsh is part of the libvirt project which is an abstraction layer that 
sits on top the various virtualization technologies out there.

If you don't have something like "qemu-kvm" then you are probably running 
RHEL 5.x where the default hypervisor is Xen. If that is the case then you 
should have the xen kernel installed (test with "rpm -q kernel-xen").

In RHEL 6 kvm became the default (and only supported) virtualization 
technology for the host.

Using libvirt over the native tools means you can manage and script your 
virtual infrastructure independent of any specific hypervisor i.e. "virsh 
start X" will always start virtual machine X no matter if it's a kvm or xen.

Regards,
   Dennis