Running KVM inside of KVM

wlanboy

Content Contributer
Jarland posted a good tutorial about turorial for that.

On Debian 7 you have to enable the virtual NAT network:


#List all virtual netoworks
virsh net-list --all

#Network default marked as autostarted:
virsh net-autostart default

#Start network
virsh net-start default

Quite some fun to run a FreeBSD KVM inside of a Debian based KVM:

 
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Erawan

Member
How about a virtualbox inside a kvm inside a kvm inside a kvm inside a kvm inside a kvm

Lol, someone posted about that long time ago at LET

10 virtualbox running inside another
 

WebSearchingPro

VPS Peddler
Verified Provider
The bad thing about the whole KVMception thing is it generates I/O load and CPU load per instance so your essentially using x amount more resources than a normal user. 
 

scv

Massive Nerd
Verified Provider
The bad thing about the whole KVMception thing is it generates I/O load and CPU load per instance so your essentially using x amount more resources than a normal user. 
The CPU usage is actually very minimal. CPUs with virtualization extensions (i.e. CPUs capable of running KVM) will actually run the instructions on bare metal, not interpreting or recompiling them. When nesting KVM these instructions are equally available inside the guest, so additional guests have only the hypervisor overhead which is very minimal.

The I/O load on the other hand would be a dead giveaway to shenanigans inside the guest. ;)
 

Magiobiwan

Insert Witty Statement Here
Verified Provider
I read somewhere [Citation Needed] that with an AMD CPU, Nested Virtualization IS possible. Its just really slow.
 

scv

Massive Nerd
Verified Provider
I read somewhere [Citation Needed] that with an AMD CPU, Nested Virtualization IS possible. Its just really slow.
It works on both AMD and Intel[1][2]. There is a performance hit but it's not as bad as one would think.
 
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earl

Active Member
yeah with AMD the RVI instruction set for nested virtualizations is not disabled where as in intel VT i believe EPT is.. while its good for testing but too slow for real use..

--Just to add I highly doubt that the provider would be willing to enable nested on the node.. cause techincally you can install proxmox then install windows in a KVM guest and offer windows VPS? you could probably resell part of your VPS as well not that you need KVM for this but just a thought.
 
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peterw

New Member
Did not know that this is possible. Is this really bad? I know many people running openvz or lxc inside of their kvm vps.
 

earl

Active Member
Did not know that this is possible. Is this really bad? I know many people running openvz or lxc inside of their kvm vps.
Should have taken better notes, but if memory serves me correctly.. in a nested proxmox with Debian as a KVM guest I was gettting DD at around 5MB/s.. Power of your CPU could probably have an effect on the performance as well..

if anyone has proxmox and looking to try.. you dont really need nested to try getting KVM inside KVM, just choose core2duo as CPU type and disable "KVM hardware Virtualization" under the VM options. This worked on an Pentium E2180

Don't think I got windows server working but XP was fine and Debian and Centos worked as well..suppose if you experimented a bit maybe you can get better performance..
 

InertiaNetworks-John

Inertia Networks, LLC
Verified Provider
An interesting concept. I'm sure that it will allow you to also have more control of your environment. (Encryption, partitioning, backups)
 
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