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Mridang Agarwalla
Asked: 2011-08-26 23:52:16 +0800 CST

KVM on multiple servers

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I'm using KVM for virtualization on a couple of Ubuntu servers but each physical server runs a bunch of VMs. Is there a way I can scale my VMs across physical servers? Does KVM support this? Is there an alternative tool that does this?

I know that VMWare, Citrix and RedHat have their own scalable hyper-visors but they are darn expensive.

Here's an image that illustrate what I mean:

enter image description here

Thank you.

Here's a scenario. We're going to be serving Django site using Apache and Postgres. Nothing more complex than that. In order to handle traffic spikes, I'd like to add more VM guests automatically to handle the extra load. Doesn't EC2 do something like this? This is pretty much what my needs are.

virtualization linux unix kvm-virtualization scalability

2 Answers

  1. generally you cant scale single vm's across physical machines (eg vertical scaling) no matter what hypervisor software you are using, it's just a physical impossibility right now

    if your thinking horizontal scaling where you create extra VM's to balance load then sure thats totally possible

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  2. how do you mean "scale"? You can add more VMs as long as your hosts allow that, and add more hosts when you run out of resources. That's what "scaling" means in this context, and it's possible with any KVM implementation, though a nice management tool makes things easier and much more manageable.

    If you mean make a single VM as powerful as the sum of the hosts it's running on, then no, this is science fiction.

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