IBM's RISC-based iSeries and pSeries servers are now available pre-installed with Linux. Sun's been taking limited steps toward Linux on RISC, by adding Linux APIs to Solaris. HP's RISC servers, on the other hand, don't run Linux at all. So what are the rationales behind these disparate approaches?
On IBM's part, the differences extend to the platform level. At one time, IBM supported only proprietary OS on its two RISC-based systems: the AS/400, now renamed iSeries, and RS/6000, now known as pSeries.
IBM's AIX 5L OS brought the ability to run recompiled Linux programs on pSeries. Then last fall, IBM introduced the 630LX, a pSeries server specifically designed to run Linux.
Meanwhile, IBM's iSeries "business servers" have the ability to run both OS/400 and Linux. "So, if you buy an iSeries, you can carve it up into multiple different OS/400 and Linux servers," says Craig Johnson, iSeries product marketing manager for Linux. Similarly, IBM's CISC-based zSeries mainframe servers are able to run z/OS, VM and Linux.