We've announced Windows Server 2003 DataCenter Edition R2 - which is quite a mouthful.
There are two big changes here. One is the systems that can run DataCenter Edition; previously the DataCenter High Availability programme meant the OS was only available pre-installed on qualified hardware systems, with special support arrangements. That route still exists, but now system builders and Volume licence customers will be able to install it, outside of the high availability programme.
Number two is that it has licenses for unlimited Windows VMs ...
Now... I was watching one of the Winhec sessions "Windows Server Virtualization Scenarios and Features" I was struck by stories of customers who just can't have any more servers. There isn't space, or the power grid can't cope. That's a pretty horrendous state of affairs - not do all those servers create a lot of CO2 emissions, but the air-con to dump the heat they create causes even more. In much of the world, for much of the year, more fossil fuels are being burnt to heat the building. When you check, many servers run at 10-15% utilization and those not using SANs typically have multiple disks to get spindles for throughput and redundancy... This is a problem crying out for virtualization. The VHD files for many virtual machines can be stored on a SAN using multiple spindles, but requiring fewer drives overall, so less power and cooling. A system with 4 or 8 processors doesn't use 4 or 8 times the power of a single processor system, so even if virtualization meant one VM per processor there would be a saving. But the ratio is more likely to be 3-5 VMs per processor... Or rather per core - with quad core 64bit processors you could be looking at 12-20VMs per processor - 100+ VMs on an 8 proc system. And with DataCenter supporting 1TB of RAM you could have 250 VMs with 4GB each. Note that Longhorn server’s virtualization is going to be 64 bit only – so you’re planning large systems you need to look at 64 bit. Of course if you ran that many VMs and a node failed. You'd really need clustering; and with 8 way clustering in DataCenter you could have 1000 VMs on a cluster. You could get rid of a lot of servers that way... now if only someone would find a way of using that waste heat.