June 21, 2013

Twenty five years ago today IBM introduced a new computer system. Many folks didn't pay much attention, after all this is what IBM is known for, computer systems. It had an unassuming name, another thing IBM is very good at, they called it the AS/400. The system wasn't really completely new as it took the System/38 as a starting point, merged in the best of the System/36 and the languages from both of them. Additionally they upgraded those languages, the database, the command language, and the commands themselves as well. Included was a clear migration path from the two predecessor systems with thousands of additional applications ready to roll. For its time it was an incredible machine!

Compared to its predecessors the AS/400 was an impressive performer and gave a large amount of room for growth from those earlier machines. Although at 96MB of memory and 27GB of disk the upper limits of the day seem nearly comical today! But this machine was far more than just hardware and an operating system with a build in database and some languages. One of the pieces that was little understood, but there right from the beginning, was a layer of virtualization.

Back in 1988, the software believed the system ran on 128 bit hardware with a single level address space from 0 to 2^^128! But the processor back then was a proprietary 48 bit system, and had such low actual performance that it was surrounded by coprocessors, called IOPs, that did all the heavy lifting of I/O. Way back then this virtualization wasn't used for LPARs or sharing resources, it's focus was on preserving software value, and it worked! We were able to migrate software from release to release and we're still going a dozen releases later. No re-writes and in most cases not even a recompile, it just worked.

And what was happening underneath those releases? New hardware of course! We moved from white servers with 48 bit CISC processors to black ones with 64 bit RISC CPUs. From unspeakably low speeds to chips at 5GHz plus, with 8 complete CPUS on a single chip. Each chip by the way now contains more L3 cache than that first server supported in total RAM! We grew from servers with only one processor to servers with up to 256 of them! The new processors are so fast that those IOPs are a thing of the past, now emulated in software. Over the years we added and then outgrew Token Ring networks. We got Ethernet adapters that chugged along in single digit Mb rates and now support speeds of 10,000 Mb. Despite our fondness for them, we've finally dropped the old Twinax devices completely. While disk units shrunk physically from massive 14" platters down to 2.5 inches their capacity grew from 400MB to 570GB and larger! And we've added SSD storage to the mix for even better performance. Total storage supported is now so large almost nobody even does the math.

But the system has gone so much further than simply bigger and faster. That layer of virtualization, boy has that come in handy! Years and many releases ago it enabled the system to begin to virtualize resources. Initially the system could share memory and processor resources and move tape and optical ones. Today partitions can be 100% virtual and can even be moved between servers while active! Partitions can be installed from network resources and support for external storage has become as good as internal disk. From the 'one to a server' days we can now support literally hundreds of partitions per physical server.

And then there are the things that servers do best, run software! In 1988 it was RPG or COBOL and record access to the database. At 25 years we can still do that but we've also gained C, multiple web serving options, PHP applications, MySQL support, full SQL capability, and several high performance Java versions as well. We're more open than the open source guys! We no longer edit our source in 24 x 80 character based interfaces or head for the command line for every operations issue.

In the 25 years we've gotten a new server with its own name: "Power Systems" and a new name for the operating system: "IBM i". We've joined forces with the AIX folks to enhance virtualization allowing both AIX and IBM i to run on this new server. Also don't forget we can run Linux partitions as well! The future is bright for Power Systems and IBM i.

Happy Birthday IBM i! I can't wait to see what the next 25 years will bring!

- DrF