The developer of this database engine claim that more relational data is stored in this database across the world than any other. The largest OLTP database in the world (in terms of data size, is the Land Registry, at 23,101 GB) is also stored using this database (according to the Winter Corporation survey). So is the largest in terms of millions of rows (UPS; 89,621 million).
So what is this database that no-one talks about? The Register’s Developer site has an interesting article laying out these facts and more, and questions why DB2 does not receive more press or advertising from IBM. They suggest that IBM has possibly become complacent and feel that they have no need to advertise or push the product – why should they if they are already the database market leader (in some but not all areas). Seems a dangerous policy to me.