Block storage and replication in Hadoop - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is block storage in Hadoop?

Block storage in Hadoop means breaking large files into smaller fixed-size pieces called blocks. These blocks are stored across different machines to manage big data efficiently.

beginner

Why does Hadoop replicate blocks?

Hadoop replicates blocks to make sure data is safe and available even if some machines fail. Replication copies blocks to multiple machines to avoid data loss.

intermediate

What is the default block size in Hadoop HDFS?

The default block size in Hadoop HDFS is usually 128 MB. This size helps balance between managing many blocks and efficient data processing.

intermediate

How does replication factor affect storage in Hadoop?

Replication factor is the number of copies of each block. A higher replication factor means more copies, which increases storage use but improves fault tolerance.

advanced

Explain how Hadoop ensures data reliability using block storage and replication.

Hadoop splits files into blocks and stores them on different machines. It makes multiple copies (replicas) of each block. If one machine fails, other copies keep data safe and accessible.

What is the main purpose of block replication in Hadoop?

A To speed up file deletion

B To improve data safety and availability

C To reduce the file size

D To compress data blocks

Replication creates copies of blocks to protect data if machines fail, ensuring safety and availability.

What happens to a large file in Hadoop before storage?

A It is split into smaller blocks

B It is stored as one big file

C It is converted to text

D It is deleted

Hadoop splits large files into fixed-size blocks for easier storage and processing.

What is the typical default block size in Hadoop HDFS?

A 10 MB

B 1 GB

C 64 KB

D 128 MB

The default block size in Hadoop HDFS is usually 128 MB.

If the replication factor is 3, how many copies of each block exist?

A 3

B 2

C 1

D 4

Replication factor 3 means three copies of each block are stored.

Which of these is NOT a benefit of block replication?

A Data fault tolerance

B Increased storage space

C Faster data deletion

D Data availability

Replication does not speed up deletion; it increases storage use but improves fault tolerance and availability.

Describe how Hadoop uses block storage and replication to protect data.

Think about how breaking files and copying blocks helps keep data safe.

Explain the role of the replication factor in Hadoop's data storage system.

Consider how more copies affect storage space and data safety.