The correct answer is option C (Facebook). Facebook is using Hadoop for data warehousing and they are having the largest Hadoop storage cluster in the world. Some of the properties of the HDFS cluster of Facebook is:
- HDFS cluster of 21 PB storage capacity
- 2000 machines (1200 machines with 8 cores each + 800 machines with 16 cores each)
- 12 TB per machine and 32 GB of RAM per machine
- 15 map-reduce tasks per machine
If you want to learn Hadoop, I recommend signing up for this Big Data course by Intellipaat.
You can watch this video on Hadoop by Intellipaat to get a quick start with Hadoop: