I have recently been experimenting with Xen after spending a year with OpenVZ. I decided to try out XenServer instead of community Xen because of the commercial support available. XenServer is available for free but with certain limitations controlled by license.
However, I stumbled into problems activating the XenServer license. Turns out that if you wish to activate it, you can use the self-service page that they provided. Unfortunately, that page requires a certain file that can only be obtained by using XenCenter, which only runs on Windows.
It took a few days of looking for information on how to generate that file without XenCenter to no avail till I finally contacted Citrix on their forum and was asked to contact them directly. They told me that they will generate the license for me manually and they will put in a request to make available a non-XenCenter way of gathering the information required to generate the license.
I thought that it was pretty dumb for a virtualisation company to force its users to use Windows. However, since they were nice to me, I would give their product a chance. So, after waiting for a week, I finally received my license in the mail.
The license that they gave me is valid for a year and this buys me time because I think that I will move over to community Xen at some point. I do not wish to go through this hassle of generating manual licenses each year. This brings to mind the whole concept of licensing Open Source Software, which I shall write about later today.
Debian stable comes with Xen 3.2 at the moment while unstable has Xen 3.4, which has many more advanced features while XenServer comes with Xen 3.3. The next version of Debian is due to be released some time this year or early next year. So, I think that once Squeeze stabilises, I will migrate over to community Xen instead.
I think that controlling software distribution through licensing is dumb.