Block Scanner HDFS

0 votes
What is the role of Block Scanners in HDFS?
Jul 31, 2018 in Big Data Hadoop by Data_Nerd
• 2,390 points
746 views

1 answer to this question.

0 votes
Block scanner runs periodically on every DataNode to verify whether the data blocks stored are correct or not. The following steps will occur when a corrupted data block is detected by the block scanner:

First, the DataNode will report about the corrupted block to the NameNode.
Then, NameNode will start the process of creating a new replica using the correct replica of the corrupted block present in other DataNodes.
The corrupted data block will not be deleted until the replication count of the correct replicas matches with the replication factor (3 by default).
This whole process allows HDFS to maintain the integrity of the data when a client performs a read operation.
answered Jul 31, 2018 by kurt_cobain
• 9,390 points

Related Questions In Big Data Hadoop

0 votes
1 answer

Is a HDFS block sequential ?

It seems like you are confused between the ...READ MORE

answered May 21, 2018 in Big Data Hadoop by nitinrawat895
• 11,380 points
638 views
0 votes
1 answer

How Hadoop distributes block writes into HDFS?

So, what happens is the slave node ...READ MORE

answered Aug 16, 2018 in Big Data Hadoop by nitinrawat895
• 11,380 points
171 views
0 votes
1 answer

what are the typicall block sizes in HDFS

HDFS is a block structured file system ...READ MORE

answered Apr 8, 2019 in Big Data Hadoop by Gitika
• 65,950 points
721 views
0 votes
1 answer
–1 vote
1 answer

Hadoop dfs -ls command?

In your case there is no difference ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by kurt_cobain
• 9,390 points
2,993 views
+1 vote
1 answer

Hadoop Mapreduce word count Program

Firstly you need to understand the concept ...READ MORE

answered Mar 16, 2018 in Data Analytics by nitinrawat895
• 11,380 points
7,893 views
+2 votes
11 answers

hadoop fs -put command?

Hi, You can create one directory in HDFS ...READ MORE

answered Mar 16, 2018 in Big Data Hadoop by nitinrawat895
• 11,380 points
62,562 views
0 votes
1 answer
0 votes
1 answer

How does the HDFS Client knows the block size while writing?

HDFS is designed in a way where ...READ MORE

answered Mar 27, 2018 in Big Data Hadoop by kurt_cobain
• 9,390 points
273 views
0 votes
1 answer

InputSplit vs HDFS Block

By definition Block – Block is the continuous ...READ MORE

answered Jun 1, 2018 in Big Data Hadoop by kurt_cobain
• 9,390 points
2,849 views