AIX: 20 Years Down, Many More to Go

Published: January 26, 2006

by Timothy Prickett Morgan

It can be honestly said that IBM had to be dragged kicking and screaming into the Unix market. Not once, but twice. First in 1986 with the RT PC and then again in 1990 with the RS/6000. But starting in 1997, with its first 64-bit PowerPC processors and a substantially improved AIX 4.3, Big Blue became a credible Unix player. While IBM's RS/6000, pSeries, and p5 servers have to take a lot of credit for the ascendancy of the AIX platform in the Unix space, the AIX Unix variant, which turned 20 last week, deserves some of the credit.

I said some. You cannot underestimate the effect of IBM's Power-based server hardware on its success in the Unix market. In the past few years, through brutal price and performance competition, IBM has pulled alongside Unix juggernauts Sun Microsystems and Hewlett-Packard. That price competition has been enabled, in part, by the sharing of a common Power-based platform with the iSeries line, which runs the OS/400 and i5/OS operating systems. IBM has a monopoly on this iSeries platform, and it can charge a pretty hefty premium for the hardware and software used in the iSeries, which allows it to aggressively price its similar AIX-based Power platforms. Without the iSeries, IBM would not have been able to be as aggressive in the Unix market. Period. Unfortunately for IBM, the iSeries market has shrunk by half because the need to charge such a high premium to subsidize its Unix server business has made the iSeries uncompetitive with alternative entry Windows, Unix, and Linux platforms. iSeries customers love their RPG and COBOL applications and their DB2/400 database, but love can only be so expensive. In any event, because of IBM's aggressive roadmap, the iSeries buffer, and the delivery of dynamic logical partitioning and other sophisticated technologies in the AIX-p5 product line in the summer of 2004, IBM took the lead in the Unix server market and accounts for most of the growth this market saw last year.

This is truly remarkable for such a former also-ran in the Unix space. And it seems likely that even if Sun can stabilize its Solaris platform sales as it shifts increasingly to Opterons and new product lines like the "Niagara" Sparc T1s and if HP can grow its HP-UX sales on Integrity, IBM will, from here on out, remain neck-and-neck with the former leaders in the Unix space. This will be a three-horse race for a long, long time unless something radical happens. IBM will continue to rely on its hardware to give it an edge--although for many workloads, AMD's Opteron processors will give the Power5 and Power5+ chips a run for the money and IBM may not retake a solid lead until the Power6 chip comes out in 2007.

So what is in store of AIX in the coming years, and how will IBM use its Unix operating system to further differentiate its pSeries family servers? According to Satya Sharma, who holds the title of distinguished engineer and who has been in charge of AIX development in the Austin, Texas, labs where many Power chips and AIX were developed, Big Blue has big plans for AIX. Sharma should know. He has been working on AIX in one form or another since 1993, when IBM developed its RS/6000 PowerParallel machines (remember Deep Blue playing chess?), and has been in charge of AIX since 2000, when IBM was readying AIX 5L for market on its Power4 dual-core processors.

Because IBM is so gung-ho about the open source Linux operating system, it is easy for AIX to get drowned in the Linux cacophony. Linux has run in partitions or as a standalone operating system across its entire eServer product line for the past several years and accounts for a lot of the growth in server sales, particularly on its zSeries mainframes and xSeries X86 and X64 servers and to a lesser extent on its pSeries and iSeries Power machines. Being a community developed, open source operating system has many advantages, Sharma concedes, but IBM also thinks that there are significant advantages to owning both the hardware and operating system platforms. "The Unix server market is a $20 billion market, and the Linux server market is a $7 billion market, and we are going to play in both," explains Sharma. "But AIX is the operating system that IBM controls, and that means as we add features in hardware, AIX can fully exploit those features when they are announced." By contrast, Linux is a community developed operating system, and support for many hardware features often lags the initial release of a new Linux kernel. To be fair, that has more to do with the way hardware vendors like IBM disclose information to the open source community. If IBM gave Linux developers the same lead times it gave its own AIX developers on a new feature, there would be no Linux lag or it would certainly be a lot smaller.

In the fall, IBM quietly announced to customers and partners its Unix Systems Agenda, which lays out IBM's commitment to Unix and delivering server platforms that run it. While not disclosing all of the details in the roadmaps, Sharma says that the current AIX roadmaps go out to 2011, and that IBM plans to put out a new version or release of its Unix platform every two to three years. (The difference between a version and a release is a matter of argument between IBM's technologists and marketeers, and is supposed to be based on how much new functionality is added to AIX. If the technologists had won this argument, then AIX 5.3 would have been AIX 6.0, since it had a lot of new functionality, but given that IBM is on the Power5 chips, marketing clearly wanted AIX 5 and p5 servers to have "five" in their names.)

Sharma says that the next major release of AIX is due in the second half of 2007, which roughly coincides with the delivery of IBM's Power6 processors. He won't say what the name is because IBM has not yet decided. "There will be significant innovations going into this implementation of AIX operating system," says Sharma, "so much so that we are wondering whether or not we should call it AIX 6 or not." It stands to reason that this platform will be called AIX 6, probably without the "L" for Linux because Linux affinity is no longer an issue. People don't want a Linux recompilation environment that sits inside AIX, which is what IBM was peddling in 2001 when AIX 5L first came out and the pSeries platform did not realty support native Linux as yet. What they want is to run Linux, and IBM has dynamic, logical partitioning on its Virtualization Engine hypervisor to do this on both the pSeries and iSeries platforms. Technically, it should be called AIX 5Li, since both Linux and i5/OS (formerly OS/400) run on the p5 servers these days. AIX 6 is cleaner, and given that a new hardware platform is coming, I expect IBM to peddle AIX 6, i6/OS, and Linux 2.6 on the Power6 platforms. (That's a lot of sixes, and don't go all numerological on me.)

Sharma is cagey about what will be in the future AIX, but it is going to have new features that allow operating systems and the applications that run on top of them to be more stable and reliable. "The hardware reliability is getting pretty darned good, and is approaching that of a mainframe," says Sharma. "But the OS and application reliability of Unix"--and he obviously meant all Unixes, not just AIX--"is not as good." To that end, IBM is taking another page out of its mainframe playbook, and it will be adding fault isolation and other z/OS features to AIX. Like other Unixes, AIX has a single address space for the kernel, the file system, and the drivers. With the future AIX, IBM will give these different parts of the operating system their own separate memory spaces, so crashes in one area do not take down the whole operating system, and therefore the applications that run on top of them. Specifically, a feature called "storage keys" for managing these separate memory spaces will be pulled from the mainframe into AIX. According to Sharma, 75 percent of the crashes that all Unix customers experience if Unix were retooled in this manner.

In the meantime, Sharma says that IBM is preparing a maintenance release for the current AIX 5.3 that will be put out some time in the second half of 2006, which will allow the Virtualization Engine hypervisor to span multiple, physically separated servers and allow workloads running in a logical partition on one machine in either AIX or Linux to be passed to another machine's AIX or Linux partitions, on the fly and over the network. This feature is tentatively called "partition relocation," and it is similar in concept to the VMotion feature of VMware's ESX Server for X86 and X64 servers and a similar feature expected in the open source Xen 3.0 hypervisor for X86 and X64 platforms.