Aperture

We all know, and some of us even used virtualization software such as VMWare Workstation, VMWare GSX Server, Microsoft Virtual PC or Virtual Server, but very few of us got access to real hardware assisted virtualization. Except from proprietary systems such as IBM Regatta (Alpha based mainframe), hardware virtualization was nearly inexistent in entry-mid level WinTel server market. Things started to change a few years ago when hardware assisted virtualization was build in by entry-mid server CPU manufacturers (Intel & AMD). Another option became available at the time: VMWare ESX Server.

VMWare ESX became the preferred software to manage hardware assisted virtualization. With support for virtual networks and clustering, ESX started to conquer market share. Companies started to talk about high availability (via clustering of virtual machines), server consolidation (no need for a physical platform to host Active Directory Services, PKIs, IAS, Web or other non storage demanding roles), platform on demand (with a few mouse clicks you have a full blown system running or revert to a previous system snapshot), etc.

As with any new technology, features available for high end machines, graduately migrate to mid-range and eventually to entry (SOHO) market. You can see the same similarity in auto industry: Features available only in BMW 7-series 5 years ago are now common to BMW 3-series, and the examples may continue. Same was with the x86 CPU manufacturers. Both Intel and AMD started to introduce Hypervisor instructions in CPUs dedicated to entry level servers or even home users. Adding that up to the fact that is almost impossible to buy a single core CPU today, you now have, like it or not, used it or not, multicore CPUs with built in Hypervisor functions.

That means, if you choose your products correctly, you can also put the Hypervisor @ work. If you’re not fond of having a server in your home, Hypervisor is still available for the normal home user by acquiring any X38 or X48 chipset based motherboard and latest Intel desktop CPU. You’ll see the “Intel Virtualization Technology” in your system BIOS waiting for you to enable it.

Hardware is there, so…. How do I used it? Microsoft (which we all love and hate) thought about this and released the “Hyper-V” technology. Hyper-V is currently integrated with Windows Server 2008 line of products (including Core versions). Hyper-V is not something you can add to a system after the OS is installed. Hyper-V must be selected when you install Windows Server 2008, otherwise, you’ll never have the option to add the Hyper-V role to your machine.

Hyper-V was first introduced as Beta version in February 2008, Release Candidate followed by end of May 2008 & finally the RTM (Release To Manufacture) was available for download as of mid-June 2008 and mid-July via Windows Update. Microsoft is new on the market with support for Hypervisor (hardware assisted virtualization), therefore, the transition between Beta, RC and RTM was not as smooth. A lot of people (including myself) experienced problems with migration between major version of Hyper-V. After the upgrade from Beta to RC, the virtual machines already present failed to boot with General Access Denied Error. For few people working around with virtual hard drive NTFS access list, did the job, but for the majority, the only option was the reinstallation of Windows Server 2008.

Same thing happened after the upgrade from RC to RTM. Reinstall the OS. Therefore, in this moment if you plan to user Microsoft’s Hyper-V, install the OS, download the Hyper-V RTM package from Microsoft site (search for KB950050 or look here for latest version: http://www.microsoft.com/hyper-v) and deploy your virtual machines after the upgrade to Hyper-V RTM.

My previous virtualization platform was only software based on VMWare GSX Server, and I can tell you that virtual machine performance is way up to the sky using Hypervisor. The only down side of Hyper-V is that the role can be added only on Windows Server 2008 x64. No release is planned for x86 versions. Hyper-V has three main components: the Windows Hypervisor, the virtualization stack and the virtualized I/O model. Windows Hypervisor creates the hardware partions (CPU resources, memory) upon which each virtual part of code will run on. Windows Hypervisor has direct control on Hypervisor instructions that are built within your CPU and chipset.  Virtualization Stack and the Virtualized I/O offer interaction with Windows itself and different hardware partitions that are created.

Virtual Server 2005 will have a pretty smooth migration to Hyper-V as virtual hard drives created in Virtual Server 2005 (*.vhd) can be easily imported in Hyper-V Manager interface (the operation cannot be undone). I wish I had the same option for virtual hard drives created under VMWare GSX Server….

Now, since the introduction of Hyper-V, it is very convenient for companies to make use of a Windows Server 2008 x64 feature which is for free, therefore the main competitor, VMWare released a free version of his flagship product (VMWare ESX Server). The free version is called VMWare ESXi Server and can be downloaded since August 2008.

This is one thing that makes you love Microsoft. They have resources to push the market. Same thing happened when Microsoft announced the release of Virtual Server for free. Immediately, VMWare release VMWare Virtual Server (GSX Server follower, as GSX was EOL) for free.

Advantages of ESXi Server over Microsoft Hyper-V are the incredibly small HDD finger print (takes only 35 MB) of disk space and the huge experience of VMWare in Virtualization courtyard. On the other hand, ESXi is not an OS, is only a Hypervisor, meaning that the machine which had ESXi installed can only be used to create other virtual machines. ESXi does not install on top of Windows, Unix of any other OS. ESX is a stand alone Hypervisor driver with a GUI-less OS structure. After ESXi is installed, you are taken to a screen where you setup the network configuration and system security. After restart, you are presented with a DOS screen that says: “to manage this ESXi server, download management tools from http://xxx.xxx.xxx.xxx”. After using your web browser to download the management tools, you may go ahead and create your virtual machines by using the DVD drive of the management PC (pretty cool feature, huh?)

The article you are reading is from a Hyper-V machine in my virtual network which uses 2 CPU cores (out of 8 physical) and 2 GB of system RAM (still out of 8 physical). The OS is Windows Server 2008 x86 Standard. Blog is running on IIS 7 with fast-CGI enabled, PHP & MySQL.

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