Amazon Cloud Support Engineer interview questions

First they asked about Hadoop and mapreduce questions, then they shifted to Java, Linux and Networking. Questions - What is file descriptor? Command to check used memory by all running tasks Command to check all processes running. Command to check stopped/off processes What is data locality? What happens in Shuffling at MapReduce phase? Say my replication factor is 3, and cluster of 10 nodes, one node fails, what happens to the file I have copied. Say my replication factor is 3, I changed it to 2, what happens to the files then. Suppose developer sends me a code to run, mapping phase completes at 100 percent, and reducing phase is stuck at 20% for 2 hours and then it completes, what can be the reason for it. How will you troubleshoot it? What is the difference between MapReduce 1 and 2? What is speculative execution? What is Garbage Collector? Is it good to use it? Explain what happens in linux between the process of switching power-on till the login screen. (boot process)