Some doubts about virtualization on kvm


Hi everybody!

I’m new in this forum, and why not say, I’m also a newbie in virtualization under KVM.
I have been reading a lot of documentation about KVM, how install it, how it works etc, but there are some aspects that I don’t understand very well, and may you can help me.

I have installed kvm on my Debian server

+] apt-get install kvm
+] modprobe kvm
+] modprobe kvm-intel

My system supports hardware virtualization, I have seen this in my /proc/cpuinfo.
Well, the first question is:

  • I have read about different types of virtualization, as native virtualization, paravirtualization, full virtualization etc, and as I can see,
    the best is full virtualization for the high performance, that is the technology used, for example, by Xen opensource, Vmware Esxi, etc.
    I guess this is related to option “-enable-kvm enable KVM full virtualization support” in qemu-system-x86_64.
    As I understand, this option enable full virtualization, in otherwise KVM uses paravirtualization ?

But I also read that in some cases use emulated devices with virtio is better for improve the performance, and I’m a little confused with this.
For example, when I need to create a new disk, for default qemu creates it with virtio, the same happens with network card.
Is not better use, for example, e1000 for network card, and sata disk for disk? Because if my system supports full virtualization, why I need emulate some devices?

  • Other question is how to create virtual machines. I used virt install for it, but I see that some people uses qemu-system-x86_64 to create them too.What is the difference? Is someone better than other.

Well, this is all.

I hope somebody can help me

Thanks a lot

Best Regards =)