Windows Server? (newbie question!)

Nope, Windows doesn't work under Xen, afaik. Even if it did, linode's deployment system probably wouldn't be able to handle its licensing requirements.

Well, according to this page (which I have in all likeliness read wrong), "Windows Server 2008" at least can run in Xen. Seeing as I know this is probably wrong, and Linode have some reason as to why they cannot, for curiosity's sake can anyone tell me as to why? Virtualization is such a fasinating thing. :)

Although I can see where you are coming from in regards Licensing. It might be possible to upload an image somehow onto another partition and boot off that, so you probably could add it to a Linode yourself, but yeah, I can certianly see why the Linode Team don't exactly offer it alongside their other offered images. :)

TC

Xen supports windoze only in HVM mode, which I don't believe linode is using.

http://wiki.xensource.com/xenwiki/XenFa … ad01769b92">http://wiki.xensource.com/xenwiki/XenFaq#head-fcb85a149da66907086cc8ba4f0793ad01769b92

Xen 3.x can in fact run MS Windows operating systems as long as the underlying hardware support virtualization extensions (Intel-VT or AMD-V).

Most Linux domU under Xen are run as Para-Virtualized Machines (or PVMs). PVMs use modifed kernels in the domU that replace all ring 0 calls (aka hardware level) with Xen Hypervisor calls (the kernel actually running on the bare metal). This is why the kernel you run under Xen is either a custom kernel (such as the ones used by Linode) or a kernel rolled by a distro that has Xen support compiled in. For instance in CentOS you would need to install and run the kernel-xen package in PVM as opposed to the standard kernel package.

MS Windows on the other hand does not have a custom kernel that understands how to make hypervisor calls instead of ring 0 calls. In order to run MS Windows under Xen you have to create a Hardware-Virtualized Machine (or HVM). An HVM is a fully emulated physical machine. MS Windows can then make ring 0 calls to the emulated physical machine as opposed directly to the bare metal or Xen Hypervisor.

The problem (beyond the potential licensing issues already mentioned) is that HVMs are not as efficient as PVMs. Since an HVM is a fully virtualized physical system the Xen Hypervisor has to do extra work for an HVM emulating all the hardware (think emulating clock ticks of a virtual cpu). As a result you can run less HVMs of the per system as compared to PMVs of the same size.

Additionally modern MS Windows based operating systems are much less tolerant of running on under-powered systems. While I have no insight into Linode's actual sales numbers I suspect the Linode 360 or Linode 540 plans are probably the most popular. When was the last time you saw a MS Windows based operating system perform well with 360MB-540MB of memory? Windows 2008 lists 512MB as the bare minimum, though it is stated that this is for basic tasks only, and recommends 2GB. Additionally Windows 2008 requires a minimum of 10GB of hard disk space and recommends 40GB. As such you would probably need a minimum of a Linode1080 to see acceptable performance from Windows 2008.

Assuming you wanted to meet the recommended specs you are looking at something between a Linode 1080 and Linode 2880 which puts you easily in the the $100+ per month ($1200+ per year) range as opposed to $30 a month ($306 a year) for a perfectly capable Linode 540 running Linux. You can easily purchase a system that meets the recommend Windows 2008 reqfor less than $1200 (the cheapest system listed on Dell's website is $279 list price and it meets these requirement). As such it simply isn't cost effective to run Windows on a hosted Xen platform in my opinion (regardless of which VPS provider you go with).

Don't get me wrong Windows runs well under Xen (if not quite as cleanly or as smoothly as under MS's virtualization solution or VMWare's ESX platform) and my company is starting a project to migrate a large portion of our MS platform to Xen (the Linux platform migration is already well underway).

Xen is a very powerful and capable virtulization platform with a very attractive pricing model (free to cheap) compared to some of the other big names in the virtualization field that is only getting better. With a few more years of polish by the OSS communities and companies such as Citrix I think it will even be a very aggressive competitor to VMWare's ESX platform (in many ways it already is).

Wow, that does pretty much explain everything I wanted to know, and more! Big thanks cburgess, much apprectiated! Seem's I will just have to stick to hunting down an old box to run at home instead, or maybe hunt down another VPS provider that offers some sort of Windows VPS (god help me, the prices are probably going to be horrible). Thanks again!

TC

Trojan:

You could always install Virtual PC or similar apps on your own PC and install Windows Server.

For what it's worth, Windows isn't really built for this "external" environment all that well. It's all about the internal LAN environments and you'll get the most out of it by setting up a couple of local virtual machines instead of trying to fire up IIS online.

You'll want to look at playing with Active Directory, Exchange, and IIS.

cburgess - that was an excellent post.

-=-

My understanding is that MS does have a kernel that can run in xen without jumping through hoops but it is internal, not available to the public, and there are no current plans to release it to the public.

I suspect that xen based hosting is really going to take off in the next few years and shared hosting is going to virtually disappear - with the exception of virtually featureless free or budget accounts, which may in fact be running inside a vps. When xen really starts to dominate, expect MS to release a kernel that makes it easier to run windows server inside xen - just like they release frontpage extensions for apache back in the day, when IIS just couldn't compete with all the apache hosts and they needed MS frontpage to work with the popular servers.

Personally though, I could care less about MS.

IIRC, there was work done with a university research group, in collaboration with MS on patching the Windows kernel to run as a PVM, specifically under Xen. There was a paper published, but they of course we not allowed to disclose too many details and MS is keeping the patches under wraps.

That work was done with 32-bit XP (Pro, I would assume).

http://blog.linode.com/2008/12/23/custo … h-pv-grub/">http://blog.linode.com/2008/12/23/custom-kernels-with-pv-grub/

Newbie question again… wouldn't that mean we could get it running now? I honestly have no clue how pv-grub works, but I take it now we can run our own kernels, or something? Opinions are greatly appreciated!

TC

@TrojanCentaur:

Newbie question again… wouldn't that mean we could get it running now?

Sure, if you have a Windows kernel patched with paravirtualized Xen (vs. the more typical HVM method of running Windows) and serial console support. Bonus points if it runs cleanly in 360mb of RAM.

Unfortunately, I doubt it exists in the real world… yet.

Why not run Linux its more stable and secure instead of Windows server. I have hired W2008 server for few months, but all software on it costs to much and takes a lot of resources. If you just want to have a remote desktop you might as well install XP Pro on it. I have that running on one of our other dedicated servers. Linode I like to use for Linux and it never shuts down or any other problems.

As per my above post the issue isn't the ability to run custom pv kernels, it is the need to an HVM kernel (as opposed to a PVM kernel) which Linode does not support.

There is/was allegedly a version of Windows XP created by MS that can run as a PVM, but it is under lock and key at Redmond (if it exists).

Eh, the whole point was as a bit of a sandbox, something to play around with. As a newbie to server administration, and since I'm aiming for a career along these lines, god knows someone's going to employ me to run a Windows Server, it'd be nice to have something to play around with in a more productive way than a VMWare instance on my aging desktop!

Thanks again though, I might just have to poke around with my Windows 2K8 licence on a local machine. Yay for free MSDN licencing!

TC

Use virtual box or purchase a copy of VMware Workstation and go nuts.

Would have been nice to have something usable though, as opposed to running off my thoughly nasty ADSL line! But you're right, I can't have it all, not on my budget, anyway. :D

TC

Amazon EC2 support windows server.