An Introduction to Virtualization

JamieX writes "kernelthread.com brings you a very cool and instructional article in An Introduction to Virtualization... The piece talks about the history of VM's, why they are becoming important again, implementation issues and most of all a look at a large number of virtualization solutions for all kinds of operating systems... many of them barely known... essentially more than you want to know about virtualization on a single page! Great read and reference."

vmWare's ESX server uses Linux Kernel?

I thought vmWare's ESX Server used a Linux Kernel. Or is it just the installer that is based on Linux.

Lack of comments.

I take it from the lack of comments that most of the slashdot crowd is unfamiliar with this stuff.

There are certain advantages to having cut ones teeth on the IBM mainframe.

Heads-up, people. This stuff is way cool. Think of it like a MATRIX you own.

Re:Lack of comments.

ABout the limit for many people here is vmware to run Windows under Linux (or vice versa), and UML because it is used by many hosting providers.

The problem comes down to the sucky IA-32 architecture which is hard to virtualize. Take a privileged mode instruction on a proper architecture, and it will trap allowing it to be emulated. Some IA-32 instructions do not trap but return different mode-dependent results. A nightmare.

For me what is interesting are domains, giving a very fine level of VMs to CPU allocation. A CPU may be reserved for a single VM or be shared by many, in turn many CPUs can be devoted to a single VM This gives very fine resource control and is what you get now on heavy iron such as the IBM Z-series or the big Sun machines.

This is why I follow the Xen project with some interest. Xen needs mods to the host OS to get around the shortcomings of the IA-32, but they are minor and well defined (replacement of some macros). It isn't there now, but maybe if they get enough people working on it, it could be very interesting indeed.

AMD64 support for virtualization?

Whilst IA-32 is not virtualization-friendly, is AMD64 friendlier or will future versions be?

A few 0.5GB or 1GB VMs here and there and 4GB starts to look rather small. So if AMD64 has good VM support it just adds value.

VMWare Vs. VirtualPC

Does any body have opinions on whether VMWare or VirtualPC is better ? I'm looking at using some sort of VM to do Windows development under the various flavors of Windows

The article omits XEN & coLinux

Oddly enough the article doesn't even mention XEN [cam.ac.uk], one of the most interesting virtualization systems. Xen is being actively developed and has also been featured on Slashdot [slashdot.org] a couple of months back when they released the first public versions.

Also omitted is the new coLinux [colinux.org], which was discussed on Slashdot [slashdot.org], too, just the other week.

Wow! New technology from 1967

IBM have been doing this on s/360 since CP/67.
It's hardly new and I can't see how VMWare can get a patent, it's prior art.

Don't forget about vservers

Don't forget about Linux Vservers [linux-vserver.org]. They allow you to have multiple virtual machines running on a single physical machine, all separated for security reasons. So you could run ftp on one, and a web server on another, and they would be as separate as physical machines. Also, I use VMware daily to run office-type applications, Outlook, and Remedy. I'm forced to by my employer, and the VMware solution let's me keep my regular linux wrapper around windows. Also, since the vpn connection takes control of the box, I still have "real" network access with my linux box.

Here's a link for Inferno

http://www.vitanuova.com/inferno/ [vitanuova.com]

Inferno was started by Bell-Labs and then sold on to Vita Nuova for commercial exploitation.

It has always been a free binary downlaod with source for userland and kernel source for pyament, but now, in the 4th edition, the whole kit and caboodle is under a dual license.