VMware ESX Server Support for the System i Is Imminent

August 27, 2007 Timothy Prickett Morgan

A month ago, I told you that IBM had initiated a Redbook Residency program to solicit volunteers to help Big Blue write up documentation on forthcoming support for VMware‘s popular ESX Server virtual machine hypervisor on System x and BladeCenter servers configured as a hybrid combination with System i servers. As it turns out, IBM sort of announced this capability on July 24, and will be delivering it on September 14, the same date that the new Power6-based System i 570 and the i5/OS V5R4M5 patched operating system for that box is also available.

The announcement that IBM would allow externally attached System x and BladeCenter servers to support the ESX Server hypervisor was not actually part of the official announcement letters, but were rather one slide in a slide deck that most of us outside of IBM never saw.

I said back in July that IBM rushed these announcements to try to provide some news cover for the Power Systems and Business Systems reorganization, which split the System i division in two and knocked Mark Shearer, formerly the general manager of that division, down a rung on the Big Blue corporate ladder in favor of two other general managers who run the new divisions. There’s no question in my mind that IBM was planning announcements in September or October once it decided to not wait until October 2008 for a Power6 launch, then date bopped around a bit, and then the company decided in the middle of the bopping to split the System i division after yet another quarter of declining sales for the System i platform and the realization that the System i customer set has two unique components. It bears reminding that the AIX, Windows, and Linux bases have different customer sets with their own requirements, too, and that the mainframe has lost anything that can really be called an entry customer and has few midrange customers left. Maybe IBM should have called it the Enterprise Systems division, throwing in any box with more than four sockets, and tossed everything with four or fewer sockets into the Business Systems division. That, of course, would be too logically consistent and probably politically impossible for any large IT corporation. But cleaving a weakened System i division in two to suit whatever needs some IBMers feel have to be met is relatively easy. Obviously. But I digress.

In any event, one of the things that got lost in the July 24 shuffle and the subsequent July 31 announcement letters was the support for VMware ESX Server, and it is only because of the announcement that IBM was looking for volunteers to help on the Redbook relating to this product that we had any inkling that something was in the works.

The important thing is that IBM is bringing support for ESX Server to hybrid System i-X64 server setups. The one page that IBM has posted describing this is here. It doesn’t really tell you what is going on, however.

“Our largest customers have 70 to 80 servers attached to their System i machine,” explains Kyle Wurgler, product manager for integrated servers for the System i product line. “And as we talked to customers in 2005 and 2006, the majority of them asked us about our plans for supporting VMware hypervisors.”

According to Wurgler, IBM has been looking for ways to support Integrated xSeries Servers and outboard System x and BladeCenter servers running ESX Server and using the System i as a disk array for that software for the past two and a half years. It would have been possible to add such support with VMware’s ESX Server 2.5 product line, which was launched in December 2004. But to do so would have required VMware to do all of the work providing an internal drive in the hypervisor that would allow ESX Server to talk to disk arrays on iSeries and System i boxes. But with ESX Server 3, VMware has embedded an iSCSI disk array link compliments of drivers from QLogic, and in September IBM will deliver support for iSCSI links between outboard servers and under-the-skin System i disk arrays. So now, IBM and VMware do not have to do anything too hard for ESX Server to see the System i as a disk array.

IBM has had the iSCSI links supporting ESX Server in a technical preview since February and did a beta program starting in May, according to Wurgler. The iSCSI support became generally available in May 2006, replacing the Integrated xSeries Adapter, a special variant of the iSeries and System i’s High Speed Loop interconnect, which I suspect is a variant of Fibre Channel but which IBM will not confirm. (Just like I think the new 12X interconnect is a variant of InfiniBand, but IBM says it is not. I simply do not believe it, because IBM would not be foolish enough to try to create new networking protocols but it would be smart enough to take industry standards and tweak them for its own ends.) By the end of the year, IBM probably had close to 1,000 customers using these links, by my estimate. It could have a lot more by now.

Starting September 14, shops running i5/OS V5R4 and wanting to run ESX Server on their outboard X64 servers will be able to apply PTF patches to i5/OS and then load ESX Server 3.0.1 on to their X64 boxes. Thanks to the patches, any iSeries or System i box with the 5XX designation and running i5/OS V5R4 with the appropriate PTF patches will be seen as ESX Server as a certified iSCSI storage array capable of supporting ESX Server during its bare-metal setup. The current ESX Server supports Windows, Linux, NetWare, and Solaris on X86 and X64 platforms; it allows for a single hypervisor to host as many as eight processor cores and then dice and slice it into virtual machines, each supporting its own operating system.

While most of the ESX Server 3 features will be supported with the initial release by IBM on September 14, the one cool feature that makes ESX Server interesting–the VMotion live workload migration facility–will not be supported initially. Wurgler says that IBM has it working in the labs, but given the fact that VMotion moves workloads around, IBM wants to test this feature a little bit more. As I explained a month ago, 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.

The plan now is to have VMotion support for ESX Server instances riding on top of iSCSI-linked System i storage available with i5/OS V6R1. This operating system is expected in the next six months or so, maybe in January, February, or March, depending on who you ask. All IBM is saying officially is that V6R1 will be available sometime in the first half of 2008.

All of the Infrastructure 3 tools that are sold with ESX Server 3, including the VirtualCenter management tool, work with the System i acting as a storage array. Only tools dependent on VMotion have been disabled.

What isn’t clear is whether or not IBM will officially support the freebie version of VMware’s hypervisor, which is now called VMware Server and which used to be called GSX Server, on the Systems i platform. But, given the architecture of VMware Server, there is little IBM can do to stop customers from using the product. With GSX Server and VMware Server, the hypervisor that supports multiple virtual machines that in turn run different operating systems actually runs inside a Windows or Linux operating system. Both Windows and Linux are supported with iSCSI links back into iSeries and System i disk arrays, and as far as these servers are concerned, the virtual machines inside those Windows and Linux operating systems are just plain old (if not somewhat large) files. The disk arrays inside the iSeries and System i machines are none the wiser.

One last thing. IBM is not trying to get ESX Server to run on Power-based systems, and VMware is not porting ESX Server to Power platforms, either. (When IBM says it is supporting ESX Server on the System i, people can get confused about what that means.) It would be very interesting to provide Infrastructure 3 tools the ability to manage Virtualization Engine hypervisors on Power-based servers, and it would not be unreasonable for such a thing to happen over time. VMware has to do something to make money, and if hypervisors are really going to be commodities, then it has to manage all of them–including its main competition on X64 platforms, the open source Xen hypervisor.

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