Analysis: Microsoft Windows Server 2008 Adds Virtualization -- In Beta Form

When the production version of Windows Server 2008 (WS08) ships -- the official launch is planned for February 27, 2008 -- it will include beta software code. Microsoft announced that Microsoft will include the beta of Windows Server virtualization (WSv) within the release version of Windows Server 2008, its updated flagship server operating system.

Why is Microsoft taking the drastic step of including beta code with the release of an otherwise finished product? According to Arun Jayendran, senior product manager for Windows Server virtualization, it's because customers are so interested in the new WSv.

There is no doubt that there's a great deal of interest in server virtualization. There is also no doubt that Microsoft is behind the competition. As the major server operating system vendor, it needs to get into the virtualization space. But rushing beta code to market may be a risky tactic. Windows Server virtualization will be an unfinished product: it will implement the hot virtualization method of the moment, hypervisor technology, in a kludgey way, and it will lack features like live migration.

Why Virtualization?
Machine virtualization is the simulation of an actual machine running in a virtualized hardware environment on top of a physical machine which acts as the host. What is great about virtualization is that virtual machines behave exactly like a physical machine when you interact with it. End users see no difference at all (and in some cases, they see improvements in performance). In addition, you can run multiple virtual machines on the same physical hardware -- sometimes up to 15 or 20 machines on the same box -- saving hardware, data center space, and power consumption.

Virtualization is taking the IT marketplace by storm. There are already several players, and all have generated significant revenues in the past few years, including VMware, the current market leader in the field, and XenSource, a Linux-based virtualization. And, of course, Microsoft. According to Microsoft, fewer than 5% of servers in the world are currently virtualized. If this is true, then the size of the virtualization market is huge.

This growth is being driven at least in part by a new approach to virtualization tools in the form of hypervisor technology. Virtualization has been around for several years, but it had at least one important limitation: In many cases, the virtualization products (such as Microsoft's Virtual Server 2005 R2 and VMware's VMware Server) needed to reside on existing operating systems. Hypervisors do not reside on top of the operating system, but are virtualization engines that are baked into the OS, reducing their overhead and providing a better virtualization model.

Hypervisors Take Center Stage
As a result, hypervisors are becoming very popular. On September 10, 2007, VMware announced that it had made a deal with server hardware manufacturers IBM, Fujitsu, Fujitsu-Siemens Computers, Dell, HP, and NEC to include VMware ESX Server 3i, VMware's hypervisor directly into the server hardware. This would make virtualization deployments simpler: Just hook up the server to your infrastructure, integrate it into your virtualization management space, and load it with virtual machines.

Meanwhile, on August 15, 2007, Citrix Systems, known for its thin-client solutions, announced that it would purchase XenSource, adding XenSource's guest OS virtualization capabilities to its existing line of virtualization products.

In this atmosphere, it was only a matter of time before Microsoft announced its own foray into the hypervisor market: Windows Server virtualization (WSv). Windows Server 2008 was due to hit the streets late this year; however, Microsoft delayed the release until February to give the Windows Server virtualization team time to include their beta code into the product. (Windows Server Virtualization is due to be official released 180 days after WS08 is released to manufacturing.)

There is no doubt that when it does hit the streets, WSv will make its own bang. Unlike Virtual Server 2005, WSv will not run on top of the operating system, but will run with the operating system, reducing the virtualization overhead on hardware. In addition to 32-bit virtual machines (VM), WSv will also support 64-bit VMs, something Virtual Server cannot do today.WSv will be managed through a new Microsoft Management console, doing away with the need to deploy Internet Information Services (IIS) on each server that runs the hypervisor -- once again reducing the overhead and making for a more secure hardware layer (see Figure 1 again). WSv will take advantage of the virtualization features that Intel and AMD have built into their processors. Virtual machines running on WSV can have up to four processor cores and up to 32 GB of RAM. Failover clustering will be available for both hardware hosts and virtual machines, providing service continuation at both levels.

Problems At The Start
There are problems that Microsoft will need to address. It will be missing some important features, such as live migration of virtual machines (moving a virtual machine from one hardware host to another without an interruption of service) and hot addition of resources while virtual machines are running, as well as overall resource reallocation based on current need -- features that Microsoft has announced will be added later.

In addition, according to Microsoft its trimmed-down hypervisor is less than 1 MB in size. But in order to run, it will have to be installed with WS08's character-based Server Core version -- a typical installation of which is more than 1 GB in size. Compare that to the newly released VMware ESX 3i, which is 32 MB altogether, and you'll see that WSv is really a "fat" hypervisor. And the hypervisor will have to run on 64-bit hardware, since WSv does not support 32-bit hosts.

On the other hand, WSv will change the way people look at virtualization. Currently, hypervisors cost a significant amount of money and single-VM hosts do not exist because no one wants to spend the money on a hypervisor to run one single workload. It just isn't cost effective.

Because of this, organizations running them need to make the most of each hypervisor installation, running as many as 15 to 20 virtual machines per host. With the hypervisor available in the OS, Microsoft will help organizations change this model by letting them determine the size of the workload to run on each hardware host. If the workload demands all of the host's resources, then the host will become what is called a "single-VM host" -- a host that is dedicated to one workload. Even with only one workload, it still helps to virtualize the workload because virtualization liberates all workloads from the physical hardware and lets you move them around from host to host on an as needed basis.

Become Part Of The Trend
The move towards hypervisors is quickly dividing IT services into hardware resource pools and virtual service offerings. Hardware is now viewed as nothing more than a pool of resources that is designed to provide sufficient processing capability for the service offerings. Service offerings -- the services that interact with end users -- are all virtualized so that you can take advantage of the benefits virtualization offers to make sure they are always available.By treating all hardware resources as host systems for virtual service offerings, you can dynamically control how they interact with users. Virtual service offerings become nothing more than policy-based workloads that can be dynamically controlled to meet demand.

Say, for example, that you are running an e-mail service. During the night, you run two virtual machines to keep the service available. In order to have redundancy and failover capability, these two virtual service offerings are running on two host servers, one each. If one fails, then the two virtual service offerings are moved to the same box for service continuity. Then, when demand for your e-mail services begin to peak, say, around 8:00 a.m. when users start coming in to work, you dynamically launch a third virtual server.

As loads increase, you launch another and another still. When loads begin to decrease, you cut back the running virtual machines. You assign hardware resources in the same way, keeping machines on standby for when you need them. The datacenter becomes dynamic because power and cooling is managed dynamically as you launch physical resources to support the need for virtual services. Your service level agreements determine the policies you create to launch machines on an as-needed basis. And you, as IT administrator, just sit back and watch the workloads pop in and out of existence as policies interact with demand.

Hardware manufacturers will also produce new offerings as everyone realizes that, in order to provide the best of any resource pool, you must have at least two physical servers using shared storage -- it is the only way to ensure service continuity for virtual machines. We'll see such 'servers-in-a-box' appear to address this need for small to medium organizations, or even only for remote sites in larger organizations.

Introducing Beta In Release Code
But with all its advantages, the version of WSv that will ship in early 2008 will be beta code -- and including beta code into a release product shows the desperation Microsoft is feeling in regards to virtualization.Placing beta code in a release product can lead to serious issues when you run it on production systems. According to Microsoft, the code will not actually be running unless you execute two included updates. However, these updates are in the Microsoft Update format (.MSU) and can easily be executed through scripts, launching the beta product on a system that is intended for a different purpose. This could lead to serious security issues and potentially compromise a system.

Of course, the attacker would need to circumvent User Account Control, the system that ensures no administrative tasks are performed without your knowledge, but given the right situations, this can be done quite easily. Why not prevent this altogether by making WSv downloadable instead of including it with the release code? This way, those who want to test it can make their own decision about running it on production systems.

So although Microsoft's rush to get into the hypervisor market is showing some results, it remains to be seen whether Windows Server virtualization can overcome its current drawbacks just by being free and keep Microsoft in the virtualization game while it catches up with the feature set of existing but costly competing products.

Danielle Ruest and Nelson Ruest are IT professionals specializing in systems administration, migration planning, software management, and architecture design, and the authors of The Definitive Guide to Vista Migration and the upcoming Complete Reference To Windows Server 2008. You can reach them at [email protected].