Cluster means different things to different people. In the context of this article, cluster is best defined as scale-out -- scale-out clusters generally have a lot of the same type of components like Web farms, render farms, and high performance computing (HPC) systems. Administrators will tell you that with scale-out clusters any change, no matter how small, must be repeated up to hundreds of thousands of times; the laziest of admins have mastered techniques of scale-out management so that regardless of the number of nodes, the effort is the same. In this article, the authors peer into the minds of the laziest Linux® admins on Earth and divulge their secrets.
For me, the most fun part of the job is in Tip 3 -- Automate Everything. Coding is fun, especially if the result is not having to type so much. Similarly, coding up APIs to access your monitoring data gives you programmatic access to your data which will simplify analysis.