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From Chiradeep Vittal <>
Subject Re: KVM + LXC on the same host
Date Wed, 11 Jun 2014 00:26:30 GMT
I thought the LXC 2.0 project uses KVM system vms on the same host as LXC containers?

From: Kishan Kavala <<>>
Reply-To: "<>" <<>>
Date: Sunday, June 8, 2014 at 11:59 PM
To: "<>" <<>>
Subject: RE: KVM + LXC on the same host

-----Original Message-----
From: ilya musayev []
Sent: Saturday, 7 June 2014 1:50 AM
Subject: Re: KVM + LXC on the same host
Thanks for the feedback, conceptually, i was not trying to address the issue of
sysvms not running on LXC.
Here is the use case as i see it.
Assume you roll out a farm of  10 KVM servers and your density with KVM is
200 virtual machines. Most of these VMs dont require independent kernel
and additional layers of virtualization abstraction. As the result, you can place
400 LXC machines and 20 fully virtualized Linux or even Windows Servers. If
you do chargeback, you can offer the LXC machines for much lower price point
since we can place more LXC containers.
Your density becomes much greater with LXC and yet you still cover the
corner case when end-user needs KVM instance.
If I will get to try this scenario - i may have to alter the KVM/LXC agent
somewhat to make it work with CloudStack, i will let you know.
Some minor changes to KVM/LXC agent will be required to make this work. Below piece of code
in createVMFromSpec (LibvirtComputingResource), deploys systems Vms in KVM and user Vms in
If we include some flag in VirtualMachineTO, it should be possible to specify which userVm
has to be deployed (KVM/LXC).

        if (HypervisorType.LXC == _hypervisorType && VirtualMachine.Type.User == vmTO.getType())
            // LXC domain is only valid for user VMs. Use KVM for system VMs.
        } else {

Alternative solution would be to run separate LXC and KVM clusters, which is
also a possibility - but usage and distribution will be uneven.
The concept of combining both technologies under one hypervisor On 6/6/14,
8:42 AM, Pierre-Luc Dion wrote:
> ilya,
> Let us know how it goes your hybrid of LXC+KVM. I'm interested to know
> how it's going,  I might try that too on the side.
> Pierre-Luc Dion
> Architecte de Solution Cloud | Cloud Solutions Architect 855-OK-CLOUD
> (855-652-5683) x1101
> - - -
> *CloudOps*420 rue Guy
> Montréal QC  H3J 1S6
> @CloudOps_
> On Fri, Jun 6, 2014 at 10:53 AM, Nguyen Anh Tu <<>>
>> That should be a good idea, Ilya. At that moment, i'm working on
>> Docker support. When it's done, we can run only Docker hosts, no need
>> to use KVM for hosting system vms.
>> Cheers,
>> --Tuna
>> Sent from my GT-N7000
>> On Jun 5, 2014 7:58 AM, "ilya musayev" <<>>
>> wrote:
>>> We are considering running KVM and LXC on the same host and
>>> hopefully control both through cloudstack.
>>> I know there are agents involved for each component, i dont know if
>>> we
>> can
>>> have a hybrid of LXC+KVM.
>>> The use case is simple, we would like the end user to pick
>>> LXC/Docker for performance, or KVM instance if he really needed all
>>> bells and whistles
>> of
>>> dedicated kernel in fully virtualized environment.
>>> Is anyone aware why we should not mix 2 workloads on the same host?
>>> Is it possible at this point in time to mix LXC, KVM and CloudStack,
>>> i assume
>> the
>>> answer is no, but perhaps there is a hack i can try.
>>> Thanks
>>> ilya

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