Sine Nomine Shows Off Solaris on System z

Published: December 6, 2007

by Timothy Prickett Morgan

In the wake of their landmark agreement to have Solaris certified and distributed on Big Blue's server lines, IBM and Sun Microsystems have given their blessing to Sine Nomine Associates for a prototype of the OpenSolaris open source variant of Solaris--which is not quite yet a full distribution--acting as a guest operating system on the mainframe's z/VM virtual environment. That prototype, which predates the Sun-IBM agreement, was demonstrated recently at the Gartner Data Center Conference in Las Vegas.

IBM and Sun inked an OEM agreement back in August that will see Big Blue certify, sell, and support Solaris first on its System x rack and tower servers and its BladeCenter blade servers using X64 processors made by Intel and Advanced Micro Devices. Then, IBM vaguely suggested, Solaris could find its way onto mainframes and Power-based servers.

SNA--the pun with IBM's Systems Network Architecture must be intended, and it is far better in Latin than No Name Associates would have been in English--wasn't waiting around for Big Blue to catch a clue on Solaris for mainframes, just like it didn't wait when it joined the small community that helped originally port Linux to the mainframe back in 1999.

According to David Boyes, president and chief technology officer at SNA and the guy who gave the presentation and demonstration of OpenZolariz (no, that is not a typo) at the Gartner event, his company did a feasibility study of moving OpenSolaris to the mainframe in 2005, and soon after Sun put out the OpenSolaris source code, it created the open source project for the mainframe port. Serious development began in November 2006, and in April 2007, the company started talking about the development effort. IBM and Sun were formally invited to the Solaris mainframe port party in June, whereby Sun joined up in a few weeks. In August, of course, IBM and Sun announced the Solaris OEM agreement.

This OpenSolaris mainframe project, which is code-named "Sirius," is distinct from the existing Polaris project to port a native version of OpenSolaris to various Power processors, including those made by IBM and Freescale Semiconductor.

The implementation of OpenSolaris that SNA has crafted for the mainframe is not a native port running on the 64-bit System z9 processors, but rather a port of OpenSolaris that runs atop the z/VM virtualization environment. IBM and commercial Linux distributors such as Red Hat and Novell support Linux in two ways on the mainframe. The first is natively, running right on top of the Processor Resource/Systems Manager (PR/SM) hypervisor that is nearly two decades old and also as a guest operating system inside z/VM partitions. z/OS, Linux, z/VM, z/VSE, and TPF all run on top of PR/SM, which is itself a hybrid hardware-software virtualization hypervisor that is a mix of microcode based largely on earlier versions of the VM platform for mainframes and hardware-assist features that have been part of the mainframe iron since PR/SM was announced in 1989 (itself a response to clone mainframe maker Amdahl's launch of the Multiple Domain Facility hypervisor for its boxes in 1985). On current System z iron, it is more difficult to port an operating system to PR/SM, and PR/SM tops out at a mere 60 logical partitions per physical box. z/VM, which runs atop PR/SM, can have thousands of partitions on a single physical machine. The current implementation of z/VM supports a maximum of 8 TB of main memory, according to SNA, and can span as far as 32 processor cores in a single partition or down to very fine granularity. How far? There is a mainframe running somewhere in the world that has 97,943 virtual Linux machines running on a single box; IBM's System z9 line tops out at 54 processors right now. That is some pretty skinny slicing.

In any event, OpenSolaris is now running atop z/VM on an IBM mainframe. You can actually see the demonstration that Boyes gave here, compliments of YouTube. The Sirius OpenSolaris port uses the LP64 C/C++ data model for 64-bit Solaris applications; the 32-bit compatibility layer for Sparc and X86 platforms is not supported. The application binary interface is the same one as is used for Linux running on z/VM, which has to be at the V5.2 level to support Sirius. The I/O layer of the port is similar to the Channel Command Word (CCW) layer used to support Linux, and the port puts the kernel and user processes in separate address spaces. It also provides a full 64-bit (that's 16 exabytes) address space for memory. A set of OpenSolaris tools (OS/Networking and Make) and GNU development tools (including GCC 4.1.1 and Binutils 2.17.50) have been moved over to the z9 architecture as part of the Sirius project as well. SNA is using the Mercurial version control system used by the rest of the OpenSolaris community to keep its port in synch with the rest of the ports. The latest Sirius instance is based on build 49 of OpenSolaris.

IBM and Sun have not elaborated on the plans to actually put Solaris into production on mainframes or Power iron, for that matter. I asked Sun if there is a plan to have the future "Project Indiana" distribution of OpenSolaris, expected in March 2008, to run on mainframes atop z/VM; I also asked if the future "Nevada" release of Solaris, presumably to be called Solaris 11 and presumably coming next year, would support System z9 and future z6 mainframes as well. In other words, I wanted to know how close Solaris or OpenSolaris is to being a normal, standard, supported operating system on mainframes. I also asked for a status report on the parallel Polaris project to port OpenSolaris to the Power architecture, which is a native port as far as I know, although it should be running on the Virtualization Engine (sometimes called Advanced Power Virtualization) hypervisor that already supports Linux, AIX, and i5/OS on IBM's Power servers.

Here was Sun's initial response: "The current announcement is around the proof-of-concept demo of OpenSolaris running on System z. The demo is in its early stages and currently includes only the core systems services of OpenSolaris, so it is premature to talk about the availability of this or other Sun software."

IBM executives were not able to comment in time for this story, either. SNA says it wants to create a Sirius sub-project on the OpenSolaris site, which should help formalize the process of expanding the Solaris port for mainframes and get the mainframe in line with Sparc, X64, and Power architectures when it comes to Solaris.

I think Solaris on mainframes is a good idea, but it remains to be seen if there is true market demand for it. What seems likely is that Sun is desperate to get Solaris endorsed by all tier one server makers, and now has IBM and Dell in the bag with Hewlett-Packard and Fujitsu-Siemens half in the bag. It is reasonable to surmise that IBM would only agree to support Solaris on X64 iron if it had a crack at trying to consolidate Solaris server workloads on System z mainframes, which have very fat profit margins compared to the slim-to-none margins on System x gear. Both IBM and Sun get a lot of their server sales in financial services accounts, which have a mix of mainframe and Sparc gear, and it is hard to believe one is going to get the upper hand when it comes to Solaris workloads. Here's a reasonable guess: While some mainframe shops may go for Solaris on the mainframe in a big way, it seems far more likely that for every Sparc/Solaris instance that moves to a mainframe partition, there will be three that move to Sun's X64 iron, one that stays on Sparc, and maybe one or two that move to IBM X64 iron.

The real issue with Solaris on the mainframe has nothing to do with the operating system or all of its nifty features, like xVM virtual partitioning (based on Xen and endorsed by IBM as well), but rather the applications running on Solaris. If many companies have been hesitant to port Sparc/Solaris to X64 iron running Solaris, how much enthusiasm will there be for mainframe ports of popular--much less obscure or homegrown--Solaris applications? If porting applications can be made easier, great. But otherwise, IBM might have just as well commissioned Transitive to make a version of its QuickTransit Sparc/Solaris emulator so the System z mainframe running Linux could support emulated Solaris application on Linux partitions. And, for all we know, that is going to happen anyway.

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