[libvirt-users] VM in a VM on kvm/qemu

[Martin Kletzander]

On Sun, Sep 13, 2015 at 11:30:16AM -0400, Digimer wrote:
>Hi all,
>
>  For development reasons, I've setup a pair of VMs (host is Fedora 22)
>running EL6 as an HA cluster. On these two nodes, I host a 3rd VM (so
>Fedora 22 -> 2x EL 6.7 -> El 6.7). Currently, 'EL' == CentOS, but I can
>switch to RHEL proper if need be.
>
>  To my happy surprise, it actually works! Of course, the two-deep EL6
>guest is slow as molasses. I don't really care about making it usably
>fast because this setup is purely to dev/test the HA cluster VMs. That
>said, a minimal EL6 install currently takes about 2 hours. So testing
>deleting/creating guests is very slow.
>

I'm guessing that's software emulated (domain type='qemu').

>  So my question is;
>
>  Understanding it will never be good performance, is there anything I
>can do to make the VM-in-a-VM faster? I tried looking for docs on this,
>looking for ways to tune, CPU/BIOS options to set, etc, without much
>luck. Most google results are about vmware and other hypervisors.
>

In case my previous guess is true, try looking up "nested kvm", which
should provide hw virt inside a VM, although that might be unstable,
not available, not working for your particular HW/setup, etc.

>  Any pointers/tips/clue-sticks will be much appreciated!
>
>--
>Digimer
>Papers and Projects: https://alteeve.ca/w/
>What if the cure for cancer is trapped in the mind of a person without
>access to education?
>
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