Why block size is 64MB in Hadoop?

The default size of a block in HDFS is 128 MB (Hadoop 2. x) and 64 MB (Hadoop 1. x) which is much larger as compared to the Linux system where the block size is 4KB. The reason of having this huge block size is to minimize the cost of seek and reduce the meta data information generated per block.

What is the default size of HDFS data block 16mb 32mb 64MB 128mb?

The default size of the HDFS data block is 128 MB. If blocks are small, there will be too many blocks in Hadoop HDFS and thus too much metadata to store.

Which makes the HDFS unique from other filesystem?

(1)Large amounts of data are laid across the disk in sequential order. (3)Metadata about each file in the HDFS is kept by the data nodes. Answer:-(1)Large amounts of data are laid across the disk in sequential order.

Why HDFS blocks are large compared to disk blocks?

HDFS blocks are large compared to disk blocks, because to minimize the cost of seeks. If we have many smaller size disk blocks, the seek time would be maximum (time spent to seek/look for an information). Thus, transferring a large file made of multiple blocks operates at the disk transfer rate.

What is HDFS explain how is it different from traditional file systems?

Normal file systems have small block size of data. (Around 512 bytes) while HDFS has larger block sizes at around 64 MB) Multiple disks seek for larger files in normal file systems while in HDFS, data is read sequentially after every individual seek.

Why does HDFS use such different locations to store file Block replicas?

Replica storage is a tradeoff between reliability and read/write bandwidth. To increase reliability, we need to store block replicas on different racks and Datanodes to increase fault tolerance. While the write bandwidth is lowest when replicas are stored on the same node.

Why is the HDFS block size extremely large compared to other file systems?

Why HDFS Blocks are Large in Size? The main reason for having the HDFS blocks in large size is to reduce the cost of disk seek time. Disk seeks are generally expensive operations. Since Hadoop is designed to run over your entire dataset, it is best to minimize seeks by using large files.