KVM, Xen comparison

Question

I have the following comparison questions of KVM, and Xen:

1. Security (how different are KVM and Xen here?)
2. Speed(I'm a long time user of VMWare Workstation but there I'd think the loss is around 50 % to the native speed, this is IMHO too much)
3. Stability (do Xen and KVM differ here much?)
4. Maintainability (how difficult or easy is ot to set up machines, and/or migrate them)

I like to setup a "virtual" machine cluster in which I probably have 3-4 virtual machines. I'd like to route all the traffic through one "router" and like to mimize the task the of the Virtual Machine Hypervisor. I'd like to run different Linux machines and maybe a few Windows Operating Systems also (Windows XP, Ws-2003-64, if I'm forced to Vista).

Are there any good web pages I have overseen?

Ok, small update. I have Xen up an running on a Debian box, but found one bug I reported. I've installed the kvm stuff also but not yet given a serious try. So am still "unshure" about "maturity"...

It's simply amazing how powerful today machienes are. Run one or two extra virtual machine does not make a difference, hard to believe....

Answer 1

I've been looking at this lately myself... with Xen Server now free I would go with Xen. VM Ware is the market leader in server virtualization but it costs a premium. With the corporate backing of Citrix on Xen Server it is going to have larger strides forward than a lesser popular KVM type of virtualization.

To answer your questions directly:

1. same
2. similar speed degradation but I would think Xen Server on bare metal would have more capability of optimization
3. Stability I would say Xen over KVM but VMWare is probably #1
4. Xen Server

http://www.citrix.com/English/ps2/products/feature.asp?contentID=1686939 http://virt.kernelnewbies.org/TechComparison http://www.webperformanceinc.com/library/reports/LoadTestingVirtualizationPerformance/index.html (VM Ware)

Those are my thoughts, hope it helps.

Answer 2

I've found XEN to be a pain because it requires a seperate kernel while KVM is just kernel module. However I've only used Virtualization on a single machine not in clusters.

Also the news about Red Hat switching over to KVM from XEN is interesting.

http://www.redhat.com/about/news/prarchive/2008/virtualization.html

Answer 3

It depend on What host you want to use. If you can use Ubuntu then KVM is a LOT easier to actually make something work. If you are a VM power user and having a Nice GUI to attach USB devices etc is important to you then you will want to go with XEN. The development branch of KVM has all the wizbang gadgets you want though they have not yet made it to the mainstream.

It also depends on what else you want the host system to be able to do. When running Xen I had trouble getting openGL applications to run on the host for instance. KVM is very unobtrusive to the host and leave everything else alone. If you are dedicating the box to nothing but VMs then this is of course not an issue.

in short: if you want easy to set up: KVM if you want fancy features: Xen.

ps: by the time I finish writing this something in KVM will have improved.

Answer 4

VMware ESXi is now available as a free download. Check out VMware.com for more details:

http://vmware.com/products/esxi/

Answer 5

Have you thought of proxmox?

Neither Xen not VMware let's you plug more than 8 vcpus to a single machine and both of them pass the vcpus as sockets to the host OS.

Instead, proxmox (qemu+KVM) can pass sockets and cores per socket to the vm.