Converting from Citrix XenServer to Xen open source

xenmigrate.py -- migratation script for moving from XenServer to open source Xen

I'm not going to spend hours explaining why you'd want to switch off XenServer to open source Xen.  The compelling reasons should let you decide if it is the right move for you.  These reasons are:

• 32bit and non-VT hardware -- you can use your 32bit hardware with open source Xen and run a whole slew of non-Windows virtuals on your older hardware.  If you're setup is like most, you have a ton of utility boxes around that can be consolidated -- and you probably don't need those running on nice beefy new hardware.
• Support -- yeah, you can get Citrix support from Citrix or their partners (I'm currently a partner, but that doesn't seem like it is going to last much longer).  So, if you run the open source version, you don't have a mediumish corporation to back you up, but you do have a massive community who run open source Xen.  The likes of Amazon and Google run Xen.  You can also find crazy people who are doing things with Xen that are years ahead of anything Citrix will let you do with it and they know way more than any Citrix support guy or any standard Citrix partner does.  You can find their help in forums, on web posts, etc.  Trust me, when I've had problems with Citrix Xen, finding the open source solution and then figuring how to finagle it back into Citrix has always been the fastest route.
• Usability -- Citrix has done their best to make you pay a lot more for features that are available in the open source product.  For a long time, live transfer of VMs was a pay only feature from Citrix while it was available in the open source version.  All sorts of things are easy to do with the open source, that can be done with the Citrix version, but are a pain.  Try snapshotting a logical volume for backup with Citrix.  Sure, you can do it, they'd like for you to pay for a NetApp or for some extra storage software.  You can actually do it from the command line, but there you go, 50% of the reason you are using the Citrix version is to get your hands on that snazzy .NET management program, and they leave a bunch of easy features out of the pretty UI so you can pay top dollar for them.
• New features -- the open source version gets released shortly before the Citrix version revs.  The open source version has all the features of the Citrix version, plus a whole bunch of stuff that Citrix won't let you use or hides in their version.  You may be asking for some instability if you try all the latest whizbang (like making your 3d accelerated graphics card work in a virtual), but you can certainly use a bunch of features that you'd have to wait for a year or two on otherwise.
• Stability -- Citrix tells you that they test their product and make sure it is stable.  But who do you trust more, the open source version that gets all the Redhat, Novell, Google, Amazon, patches, etc, or the version that Citrix sits on as their own?  Yeah, Citrix takes those patches from the others and uses them, but there you go -- are they better?
• Cost -- while XenServer is not all that expensive in the scheme of things, you could find that not paying $3000/server+$900/year is a good way to get virtualization going without any sticker shock.

Right, and you'd expect there to be drawbacks and there are.  The deal is that you are going to have to really learn about your virtualization platform.  Nothing is going to shield you from the guts of the thing and while you can get a UI, you'd better learn the command line and the text config files.  I'd recommend getting a book about virtualizaion and the Xen technology.  If you want to know nothing about the underlying platform and want to live your life in a .NET gui, then get XenServer from Citrix, or buy VMware -- you won't be unhappy because you are probably not going to get upset by the kind of restrictions that will get placed upon you.

So now that you've decided that you're kinda interested, you're wondering what to do with the Citrix XenServer setup you've partially deployed.  That's where this page really comes in.  Here at Jolokia, all of our hosting virtuals are open source Xen, but our internal systems have been running on XenServer.  I've had enough of that, however, and I'm converting the XenServer setup over to open source.  To help me (and possibly you), I've created some tools.

Citrix .xva file format (Xen Virtual Appliance) -- aka, we made our own special little format to piss you off if you want to convert away from XenServer to something different