If you’re running Big Data applications, you’re going to want to look at some kind of distributed processing system. Hadoop is one of the best-known clustering systems, but how are you going to process all your data in a reasonable time frame?
MapReduce has become a standard, perhaps the standard, for distributed file systems. While it’s a great system already, it’s really geared toward batch use, with jobs needing to queue for later output. This can severely hamper your flexibility. What if you want to explore some of your data? If it’s going to take all night, forget about it.