DATABASE FUNDAMENTALS
BASICS OF BIG DATA
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Detailed explanation-1: -This makes HDFS fault-tolerant. The default replication factor in HDFS is 3. This means that every block will have two more copies of it, each stored on separate DataNodes in the cluster. However, this number is configurable.
Detailed explanation-2: -Data reliability: HDFS creates a replica of each data block that’s on the nodes in any given cluster, providing fault tolerance. If a node fails, you can still access that data on other nodes that contain a copy of the same data in that HDFS cluster. By default HDFS creates three copies of blocks.
Detailed explanation-3: -HDFS by default creates 3 replicas of each block across the cluster in Hadoop. And we can change it as per the need. So if any node goes down, we can recover data on that node from the other node. In HDFS, Replication will lead to the consumption of a lot of space.
Detailed explanation-4: -If I want to store a file (example. txt) of size 300 MB in HDFS, it will be stored across three blocks as shown below.
Detailed explanation-5: -Each block has multiple copies in HDFS. A big file gets split into multiple blocks and each block gets stored to 3 different data nodes. The default replication factor is 3.