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To quote from the official Xen user manual (http://www.cl.cam.ac.uk/Research/SRG/netos/xen/readmes/user/user.html), "Xen is a paravirtualising virtual machine monitor (VMM), or `hypervisor', for the x86 processor architecture." It is a way to run multiple virtual machines on a single physical machines. (There are, of course, other tools that deliver similar functionality, such as VMWare (http://www.vmware.com), Microsoft Virtual Server (http://www.microsoft.com/windowsserversystem/virtualserver), QEMU (http://fabrice.bellard.free.fr/qemu/), and Bochs (http://bochs.sourceforge.net/).)
Many things that can be accomplished by using virtualization technology, in particular hardware consolidation and infrastructure simplification. Some of the ways we use Xen include:
- Server consolidation. Using Xen we migrated several low bandwidth servers to one physical machine, allowing us better use of the available hardware resources. We have been able to set up entire basic networks on a single host machine.
- Consolidation of development and testing. We are able to quickly duplicate production system configurations for testing and development. Using a VM we are able to test new software without affecting the system for other users.
- Software Demonstrations. We have some base images from which we can build a clean environment quickly. As such, setting up new machines for demonstration purposes is a simple task.
- Hosting of legacy applications. Migrate software from older hardware, even if it requires specific OS configurations. Simply create a new machine with the older software and let it go.
XenSource (http://www.xensource.com), the company behind Xen, has it's own wiki (http://wiki.xensource.com), so expect some redundancy. We would like to emphasize that we have no direct affiliation with XenSource (http://www.xensource.com) or the Xen Project (http://www.cl.cam.ac.uk/Research/SRG/netos/xen/). As such, the views, directions, and gross inaccuracies on these pages are all our own, and should in no way be taken to reflect upon the Xen Masters.
As with most wikis, this site is very much a work in progress. We hope that it is useful in its current state, and we are interested in all comments, critical or otherwise, that will help us improve it. (Or, feel free to register and make the changes yourself.)
Getting Started with Xen
- Debian and Xen - Quick Start
- Xen Project downloads (http://www.cl.cam.ac.uk/Research/SRG/netos/xen/downloads.html) If you've somehow managed to come here without first visiting the official Xen site, and are looking for their source and/or binary installs, this page has links to nightly snapshot source tarballs of stable, testing, and unstable, and well as links to nightly binary builds. Please note that if you want to use the binary installs of stable with Debian Sarge, you should take a look at the note here (http://wiki.xensource.com/xenwiki/DebianSarge) regarding xfrd.
- Sample Xen logs and dmesg output
- Common error messages
Other Xen information (on this Wiki)
- Custom Xen Kernels
- Creating and/or procurring those pesky domUs
- Links - probably too many
- Having fun with Xen - information about our demo box
- Xen dom0 + LVM + DRBD + Heartbeat
- Supported systems
- XenAdmin-Screenshots - Information and screenshots regarding our Xen administration tools
- Xen Networking/Routing
- Xen_at_ServerBeach - How we rearranged things to our liking and run Xen on ServerBeach dedicated servers
Topics related to Xen (on this Wiki)
Logical Volume Management (a.k.a. LVM)
GRand Unified Bootloader (a.k.a. GRUB)
Loop Mounting Swap Partition (no a.k.a.)