Other than the two supported Linux distributions (RHEL & SUSE Enterprise), is there any FREE alternatives suitable for Windows Server 2008 R2 + Hyper-V environment, which has the following purposes?
- Web Server
- Mail Server (POP + SMTP)
- FTP Server
- File Server
Also, I would like to ask, if Microsoft said not supporting Linux distributions other than RHEL & SUSE Enterprise, will other Linux distributions like Ubuntu Server edition and Debian be supported in later stage? Does anyone know what is the reason behind not supporting other Linux distributions (solely business consideration?) ?
"Support" in Microsoft's terms doesn't mean "it will work", it means "This is a configuration we've tried and tested, produced documentation for, produced software for (if appropriate) and will give you technical support for if you have a problem".
This hopefully explains why they limit the number of Linux distros they support.
-- edit --
My original reply was a little light hearted, but I really think its how they see it, from when I used to be a Microsoft MVP doing stuff with their virtualisation team - they used to make the distinction that lots of operating systems would work in their virtual environment, and just fine too, but they could only provide formal support for a few of those operating systems - where support means they can actually provide assistance with that configuration, guest additions, etc.
Microsoft, like any company, responds to pressure from customers. Unfortunately, for a while there they were in a big fight with Red Hat during which they weren't even responding to customer demands for Red Hat support but that has been resolved. Microsoft claims that SUSE and Red Hat are the primary distros that people are asking for and indeed the two of them make up a huge chunk of the distros in large companies (the ones that most easily get Microsoft's attention). Given how long it took and how painful it was to get Microsoft to support these two, I wouldn't hold my breathe waiting for another distro.
Technically, the issue is performance. You can build a VM on Hyper-V and run any distro you want and it will work if you use the legacy NIC and normal IDE storage controller. The problem you'll find is that the performance of the VM with the legacy NIC and the IDE controller without better drivers is poor. With the release of Hyper-V R2 (and Windows 2008 R2), Microsoft released the Linux Integration Components Version 2. Once installed, you can use the synthetic NIC which is much better and you'll find that the IDE controller performs on par with a Windows VM. Microsoft's testing and documentation for the integration components was done only with SUSE and Red Hat but many people have been able to get them succesfully installed in other linux distros and they are working fine. You just can't call Microsoft for help if something breaks or acts strange. The Integration Components were also released under GPL so other distros might themselves choose to integrate them to make things even easier.
The Integration Components are here: http://www.microsoft.com/downloads/details.aspx?FamilyID=c299d675-bb9f-41cf-b5eb-74d0595ccc5c&displaylang=en
Here's a howto for Ubuntu: http://blog.allanglesit.com/Blog/tabid/66/EntryId/22/Hyper-V-Guests-Linux-Integration-Components-Ubuntu-and-Debian.aspx