Monday, May 11, 2015

My DB2 pureScale / Parallel Sysplex Moment

Last week, members of the German union for train operators/engineers were on strike and only a fraction of trains were operating. I had to go to Zurich, Switzerland, but most of the trains on my usual route were out of service. That's when I had my DB2 pureScale or DB2 Parallel Sysplex moment.

What is special about a DB2 Parallel Sysplex or DB2 pureScale configuration? It is a data sharing cluster. If one node in the cluster or a network connection goes down and is inaccessible, the other components can pick up the work. All this is usually transparent to the application. In my case I was the application and data at the same time: Try to get me to Zurich, discuss some issues in person, get back home.

Sunset over Lake Constance
The cluster consisted of the German Railways and the Swiss Railways, connected by train tracks and ferries across Lake Constance. As the application I had a single train ticket, good within the entire cluster. As net result I got to Zurich, had the meetings, and got back home without trouble. If I had closed eyes and ears, the routing and processing would have been transparent to me. But fortunately I was fully aware of the chosen route. In the morning I took the ferry across the lake to Switzerland, then hopped on a Swiss train to Zurich, and in the evening I went back the same route. And that's when - different to "regular" applications and data - I could enjoy my DB2 cluster moment and the rerouting: Sunset of Lake Constance on board a ferry.