The ideas for the large size of blocks are: To reduce the expense of seek: Because of the large size blocks, the time consumed to shift the data from the disk can be longer than the usual time taken to commence the block. As a result, the multiple blocks are transferred at the disk transfer rate. If there are small blocks, the number of blocks will be too many in Hadoop HDFS and too much metadata to store. Managing such a vast number of blocks and metadata will create overhead and head to traffic in a network. Source: Link. ... View more