If you don't want your own Watson question-and-answer machine after watching the
supercomputer whup the human race on Jeopardy! last week, you must be a lawyer. Only lawyers think they already have all the answers.
But if you grew up watching Robbie the Robot in Lost in Space, HAL in 2001: A Space Odyssey, the unnamed but certainly capitalized Computer in Star Trek, R2D2 in Star Wars, Ahh-nold in The Terminator, and Number Six in Battlestar Galactica – we'll stop now – you desperately want a Watson: something that can answer all your questions and maybe even rule the world. So why not build your own Watson-style QA machine?
As it turns out, the basic foundations are there for the taking.
Let's start with the iron – it really isn't that much hardware, after all. With the beta version of the Watson software, IBM started out with a few racks of its BlueGene/P parallel supercomputers, a grandson of the Deep Blue RS/6000 SP PowerParallel machine that played a chess tournament against Gary Kasparov – and beat him – back in 1997. But because the Watson effort was not just a technical challenge, but also a killer marketing campaign for the current Power7-based Power Systems lineup, Big Blue eventually switched the Watson DeepQA software stack to a cluster of Power 750 midrange servers.
To have enough memory and bandwidth to store all the necessary data, IBM put 90 of these Power 750 servers into ten server racks. Each server is configured with four of IBM's eight-core Power7 chips running at 3.55GHz. That gives Watson 2,880 cores and 11,520 threads on which to run its software stack. If the DeepQA software is thread-heavy – and there's every reason to believe it is – you'll need iron with lots of threads.
The 90 servers underpinning the Watson machine had a combined 16TB of main memory, but it looks like that was not evenly distributed across the nodes. The math works out to 182GB per machine, which is a silly, non-base-2 number.
David Gondek – who was in on both the system strategy and algorithms teams behind the "Blue J" project, as Watson was known internally – tells El Reg that the DeepQA system creates an in-memory database of the information that's pumped into the system. The machines are networked together, obviously, but being a software guy, Gondek didn't know what network IBM used. I would guess 40Gb/sec InfiniBand or 10 Gigabit Ethernet with Remote Direct Memory Access (RDMA) support to speed up the communication between nodes. Gondek said that the data that's put on memory and disk is replicated and distributed around the system for both speed and high availability.
The Watson box has 4TB of data capacity, which is not all that much, really. IBM did not say if it was disk drives or flash, but if most of the data used by Watson is stored in main memory, there is no reason to use the more expensive flash technology. But what the heck. Let's use flash anyway so it doesn't run so hot.
Because Linux is the fastest operating system on IBM's Power platforms (at least according to the SPEC family of benchmarks), Big Blue chose a variant of Linux to run on the Power 750 nodes. In this case, Novell's SUSE Linux Enterprise Server 11. SLES has a lot of tuning for HPC workloads and dominates supercomputers – although Red Hat is getting some traction in HPC now as Novell's fate has been uncertain for the past year or so: SGI has certified both SLES 11 and RHEL 6 on its latest massively parallel boxes as well as Windows Server 2008, where it formerly only did SLES on prior iron.