VMware to Support Windows Partitions on 64-Bit Opterons, Xeons

by Timothy Prickett Morgan

The VMware software unit of storage array maker EMC announced this week that it intends to support 64-bit hardware with its virtual machine partitioning software, which runs on both workstations and servers. Until now, VMware had been coy about supporting 64-bit hardware or software, but the growing popularity of the Advanced Micro Devices Opteron chips, the advent of Intel 64-bit Xeons, and the delivery of 64-bit versions of Windows and Linux this year made VMware finally conclude that it was time to support 64-bit platforms.

VMware has become relatively well known as the supplier of software that can carve a single workstation or server into many virtual machine partitions. The company's products create a virtual machine environment that looks, at least as far as operating systems are concerned, like a complete 32-bit X86 machine. Using the GSX Server and ESX Server products, companies can run multiple and incompatible instances of operating systems on a single server.

GSX Server, which is the least costly of the two, installs the VMware abstraction software on top of a Windows or Linux host environment and then creates virtual machine partitions on top of that environment into which other guest operating systems can be loaded. ESX Server puts a hypervisor abstraction layer on top of the bare X86 iron and creates partitions on top of that; individual operating systems can be loaded into these partitions. ESX Server costs more and has better OS isolation. The VMware Workstation product, which is where VMware got its start several years ago, allows developers and users to have two different platforms at once on their desktops.

As far as 64-bit support goes, Michael Mullany, director of product management at VMware before and after the EMC acquisition, says that EMC is not yet ready (as VMware was not several months ago) to commit to supporting the 64-bit Itanium processors from Intel. This stands to reason, once you think about it, since the Itanium and Pentium architectures are very different. Supporting Itanium means supporting a completely different chip.

VMware does have a plan for Itanium, and Mullany says that he does not expect Itanium to take off as a volume product for at least two years. But VMware has been developing a version of its partitioning software for Itanium for three years, so presumably it can get it out the door fast should Itanium take off.

Thanks to the fact that the Opteron and Xeon-64 processors extend the existing 32-bit architecture (rather than radically changing it), it was relatively easy for VMware to support its products on these processors. Mullany says that the version of its virtualization software created for the Opteron was loaded onto a Xeon-64 machine and ran without any changes, which suggests that whatever incompatibilities have been rumored between the Opteron implementation of 64-bit memory support and the reverse-engineered 64-bit memory support that Intel will start delivering soon in its "Nocona" Xeon DP processors is very minor.

Right now, VMware is being vague about exactly when it will support 64-bit Opteron and 64-bit Xeon processors. The reason is that VMware is only now seeing customers start making their 64-bit plans for the 2005 buying cycle. There is no big hurry, particularly with Microsoft's Virtual Server 2004 running late and far behind VMware's products in terms of capability.

All VMware will say for sure is that its Workstation product, which is used mainly by developers but also increasingly by end users who have to support two different environments to do their work, will come out first with 64-bit Linux and 64-bit Windows host support on machines using Opterons or Xeon-64s. After that, Workstation will support 64-bit Linux and Windows operating systems as guests, and then eventually GSX Server and ESX Server will get 64-but host OS and then guest OS support. This rollout is expected to take 18 months.

The interesting thing is that the 64-bit support will allow companies to put 32-bit operating systems on partitions inside 64-bit GSX Server partitions or on 64-bit hardware and ESX Server combinations. Similarly, Workstation will load on 64-bit hardware with a 64-bit host environment, and then let developers create partitions with 32-bit and 64-bit operating systems running side-by-side.

For example, a developer could buy a new 64-bit workstation with Linux, and load a 32-bit SuSE instance, a 32-bit Windows NT instance, a 32-bit Windows 2000 instance, and a 32-bit Windows 2003 instance on one machine and then tweak code. This will greatly assist programmers who are moving code from 32-bit to 64-bit platforms. This is why VMware is starting first with the Workstation product and not with its servers.

For the Workstation product, EMC is not planning to charge a premium for 64-bit support, and while pricing for the server products has not been set, Mullany gave the distinct impression that it was not likely server customers would be charged a premium for VMware partitions on 64-bit machines.

The one thing that moving to 64-bits will not do is make the size of the memory block that a virtual machine can address larger. The virtual chipset abstraction used in the VMware software is capped at 3.6 GB per partition. The 64-bit memory support will allow, in theory, more partitions, but until VMware recodes that virtual chipset (which it did 18 months ago, raising the memory limit to 3.6 GB from 1 GB), partition memories will be capped. It seems likely that this time around, when VMware codes the chipset, it will make much, much larger memories, thereby eliminating the problem for a while. A 16 GB or 64 GB memory cap seems likely.