Reading Hadoop in Practice
“It was a revelation to observe our MapReduce jobs crunching through our data in minutes. Of course, what we weren’t expecting was the amount of time that we would spend debugging and performance-tuning our MR jobs.
Not to mention the new roles we took on as production administrators-the biggest surprise in this role was the number of disk failures we encountered during those first few months supporting production .
The greatest challenge we faced when working with Hadoop, and specifically MR, was learning how to (think) solve problems with it.
After one is used to thinking in MR, the next challenge is typically related to the logistics of working with Hadoop, such as how to move data in & out of HDFS.”