Double Checking Sun's Reality Check

By Moshe Bar

March 4, 2002

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On February 24 2002, Shahin Khan, Sun's Chief Competitive Officer, published an op-ed about IBM's new "Linux only" mainframe, the IBM z800. The article can be found on Sun's web site: http://www.sun.com/executives/realitycheck/reality-022002.html.

In this article Mr. Khan heavily criticizes IBM's offer, on grounds of economic and technical viability and performance issues. Right off the bat, the fact that Sun feels compelled to rebuff IBM's efforts to put Linux on the mainframe tells us that Sun perceives this offer as a serious threat to its own server sales. Sun's high-end servers, the E15000, run Solaris only, although I guess it wouldn't be that hard to make Linux run on such a machine. I for one would like to tackle this challenge.

Sun's main line of attack against IBM's offer is that a mainframe is not an open system and therefore everything — from maintenance to staff, from purchasing price to consulting — is much more expensive. Sun also questions IBM's use of its z/VM virtual operating system to host Linux on the mainframe. For almost 30 years, IBM has been selling its z/VM operating system for mainframes (previously called VM) as a tool to alleviate some of the problems of maintaining combined production and test systems, and for managing application servers for various customers or departments within the same data center. Just like VMware on the PC, z/VM allows you to run several instances of guest operating systems: Only z/VM is way more efficient in virtualizing the hardware. Usually, the cost of virtualization is just a few percent (1-3 percent performance penalty for the guest OS) because it has over the years been greatly optimized and also because it is assisted by special S/390 machine instructions to help z/VM virtualize hardware to its guest OSs. z/VM is actively maintained by IBM and is used by tens of thousands of installations worldwide. In fact, the very first relational database was first released for z/VM and only later for other operating systems.

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