I have stumbled across this and thought I would share. James wrote a great article in the TechNet Newsletter recently that explained Virtualization and what we mean by it. A lot is being made of the Virtualization element of Windows Server 2008, but our offering goes much further than that:
There has been some confusion of late about Windows Server Virtualisation, so this might be a good place to explain a little bit about it, when it will ship, what features it will have and how it compares with Virtual Server.
Virtual server 2005 is available as a free download. It only supports 32 bit guest OSes, even when utilising 64 bit servers. It developed from Virtual PC and uses the same VHD (virtual hard disk format) as does Windows Server Virtualisation. This format is available under Microsoft's "Open Specification Promise" licensing, and companies like Novell and Xen source use it - giving customers portability of images between Windows based and Linux-based virtualisation. It should also be noted that we support a number of versions of Linux on VS2005.
Operating systems run in a virtualised environment need to be licensed, and staring with Windows Server 2003 R2, licenses to run virtualised instances are included with Enterprise edition (4 instances) and DataCentre (unlimited) regardless of the virtualisation product used).
System Center Virtual Machine Manager (SCVMM) is nearing the end of its beta process and provides provisioning, management and analysis tools, and can migrate machines to VMs. SCVMM makes use of powershell, and is built using the APIs which were published when Virtual Server was released.
Windows clustering allows VMs to failover from one host to another - either in a planned way, where the system state is saved and re-loaded on a different host (which we call quick migration) or following a crash, when the guest OS is rebooted.
All benefits of VS2005 remain in the new Windows Server virtualisation. WSV has a new architecture, with a hypervisor partitioning system resources; instead of having a "host" operating system with "guests", this architecture has a "Parent" partition with multiple children. There are no device drivers in the Hypervisor - a software bus which lets a driver in the child partitions communicate with driver in the parent partition, we call these drivers "enlightenments" - VS-2005 style emulation is retained for un-enlightened OSes.
From the time it was announced, the plan was always to ship WSV with 180s of Windows Server itself. A new release of SCVMM will happen at the same time to support the new management APIs that have already been published. WSV will go into public beta when Windows Server is released. To keep to the timescales, the developers postponed three things to a later release. Support for more than 16 logical processors (we believe very few customers will want to use more than 4x4 core processors), hot add of "virtual hardware" (which require more testing of applications to prove they behave correctly when this is done) and Live migration. WSV still has quick migration described above. Live migration involves copying the memory of a running VM to another host over a period of minutes and switching over without ever writing the memory to disk.
Two blogs that are useful for more information are:
The great resource that allude to in the title is here and covers what we mean by Virtualization, the solutions and all the resources - including downloads, blogs, a Virtualization newsletter and documents