IBM, VMware Working on ESX Server Support for the System i
July 30, 2007 Timothy Prickett Morgan
The Redbook Residency program is a great idea, particularly if you are IBM and you don’t want to have to write a Redbook technical paper or longer document describing the ins and out of a new technology. So what IBM does is invite techies from around the globe to come to the Rochester Labs (in the case of System i technology) for a few weeks, where they do a deep dive on the technology and then the members of the team get together to write the Redbook manual that the rest of the customer base will look at to figure out how to use a new technology. Those participating in the Redbook Residency program often get to see a technology before it is delivered to the customer base, since IBM wants these manuals available when the technology comes out.
And such is the case with support for VMware‘s ESX Server on the System i platform. ESX Server is a virtual machine hypervisor for 32-bit X86 processors that was extended to run in 64-bit mode on X64 processors last fall. Like the Virtualization Engine on Power-based systems, ESX Server is a bare-metal hypervisor that allows multiple instances of operating systems to run in an isolated mode on a virtual slice of a physical server. (IBM’s hypervisor does logical partitions, which have some technical differences between logical machine partitions.)
In the solicitation for people to join this Redbook Residency program, IBM said that with a future release of i5/OS–which presumably means the forthcoming i5/OS V6R1–the System i server will be able to support a key feature of ESX Server called VMotion, which allows the applications running in a virtual machine on one machine to be teleported to another physical machine running ESX Server. This is a very neat feature, and it is useful for many things, like disaster recovery. In any event, many of you reading the description of the Redbook Residency program might be thinking that IBM is planning to run the ESX Server hypervisor on the System i iron itself. I will go out on a limb and say that this is not going to happen.
What IBM is most likely talking about is supporting the i5/OS Integrated File System as a data store for ESX Server partitions running on Integrated xSeries Servers and outboard System x servers connected to the System i platform through iSCSI or maybe High Speed Loop links. With VMotion, the machine running the applications and the one that will be running those applications after the VMotion teleportation have to be linked by a storage area network. What ESX Server is really doing is capturing the state of main memory in the X86 or X64 server running in the VM, moving it to a new machine, and flipping the link to the SAN from one VM on the first server to another VM on the second server. If you don’t have common, shared storage, you can’t do the VMotion, since actually moving the data across a network would be very time consuming.
As far as I know, VMware is not planning to support ESX Server on Power processors. The hypervisor is really created for X86 and X64 chips. Sources at VMware have told me that the company is working on a hypervisor for the Itanium processor from Intel, and I think one of the reasons that Intel is taking a $218 million stake in VMware, which is already owned by disk array maker EMC, prior to the company’s initial public offering is to get VMware motivated to create a version of ESX Server and the related Infrastructure 3 tools for the Itanium chip. Right now, vendors selling Itanium-based products have to create their own server virtualization hypervisors, just like IBM did for the System i and System p lines.
That said, IBM could take a similar stake in VMware and the two could work to get ESX Server running on Power chips. Stranger things have happened. But I think this is unlikely unless IBM has a plan to consolidate all of its servers down to a single set of motherboards and sockets and that it has decided to concede the hypervisor space to VMware. I think it is far more likely that IBM will put a variant of Virtualization Engine on all of its machines, including System x boxes, before it puts VMware’s ESX Server on Power servers. We’ll see what actually happens in due course.