Which is best to use on a HEADLESS Server that is going to be use as virtualization host? KVM / XEN / QEMU?

Question

Okay, The main purpose is to learn about virtualization and play around with it. However, I have a problem of determining which is best for a headless server. I want to run several Linux distributions as well as Windows guests.

On a Side Note: This is not the first time I am going to use virtualization. For more than 3 years I have been using VMWare Workstation and VirtualBox to run guest VMs

However, now I want to run VMs/VEs in a headless server as they do in industry. I know, in industry there are lot of advanced technologies are being used but, still I want to try them in SMALL-SCALE. As I mentioned before, this is purely for educational purposes.

If you're wondering what kind of system that I am going to use as my host, here are some details:

• Intel processor that supports hardware virtualization (Intel-VT)
• 8GB RAM
• More than enough Hard disk space (~1TB)

Can you give me some suggestions, directions and links for tutorials and guides?

P.S. I installed VMWare vSphere Hypervisor on my "host" and later noticed that it uses just over 1GB of RAM just to run the hypervisor. It is not an efficient solution for me because I have only 8GB RAM in my machine. Typical Linux Headless server only uses ~300MB RAM just to run. So, I prefer Linux Server. In fact I love FOSS :) :)

Solution

You mention "in industry" a couple of times. Fact is these different virtualisation technologies, along with others like OpenVZ, all get used in industry. Most of them have certain merits like:

• being able to maximise density through burstable RAM (for cheap OpenVZ VPS hosting)
• offering fair shares of the hardware (for more expensive, lower density Xen VPS hosting)
• ramming a server full of applications with the least overhead (eg LXC, OpenVZ)

You can get a fairly raw comparison of features on the Kernel Newbies' Virtualisation site but they don't really delve into industry application.

So what should you use?

Well... I think if you're doing this for educational purposes you should probably try at least two to compare their features, performance and how easy they are to set up and maintain for yourself.

I would personally suggest Xen. I use it as a customer (I have no set up of it) but I can speak for its guest performance and I know it can host Windows machines too (as long as your CPU supports vmx and the copy of Windows you're planning on installing is that for HyperVisor).

Xen should also have dom0 in the default Ubuntu kernel (that needs checking). This essentially means any install of Ubuntu can be a Xen host without having to fanny around with patching the Kernel.

But Xen reserves RAM for a machine indefinitely. If you're planning on something a whole lot more burstable (where VMs get the guts they need, when they need them) perhaps you want to look at a looser container like OpenVZ. The only problem with these is you'll need another solution for Windows.

KVM is very popular in the developer world. Simple to get going. Similar performance to Xen but I just have no experience with it but plenty of developers do (I follow several FOSS blog "planets" and there's usually at least one mention about KVM per week).

Also, you can run VirtualBox in headless mode if you're looking for something more familiar.

Comments

[tonix]

First of all, thank you very much for this inspiring answer. As you have mentioned, I should try at least two of them to get some sort of good experience. I found that OpenVZ is a good solution, if one is planning only to use Linux VMs. However, in my case, I need some Windows VMs as well. I also noticed that OpenVZ cannot run in a standalone host. When it comes to Xen, it can run in a standalone host (so I can experience a bare metal hypervisor) and supports to Windows VMs as well. Since I have only one machine to try those, I'll first go with Xen; later OpenVZ :)

[tonix]

Can you also kindly name those FOSS blogs that you follow? ("I follow several FOSS blog...")

[Todd Deshane]

Ubuntu+Xen Howto: bderzhavets.wordpress.com/2011/07/23/… ... You may also want to take a look at the open source version of Citrix XenServer called XCP (xen.org/products/cloudxen.html) It is designed to run headless and has robust API and lots of management tools (wiki.xen.org/xenwiki/XCP_Projects). The XCP toolstack (XAPI) is also being ported to Ubuntu wiki.xen.org/xenwiki/XAPI_on_Ubuntu blog.xen.org/index.php/2011/07/22/project-kronos)

[tonix]

@ToddDeshane Thanks for the information and links. Xen Cloud Platform (XCP) is something that really interest in me... :)