How does HDFS ensure data integrity of data blocks stored in HDFS?

[#1]

Does HDFS ensure data integrity of data blocks stored in HDFS?How?

[#2]

Data Integrity talks about the correctness of the data. It is very important for us to have a guarantee or assurance that the data stored in HDFS is correct. However, there is always a slight chance that the data will get corrupted during I/O operations on the disk. HDFS creates the checksum for all the data written to it and verifies the data with the checksum during read operation by default. Also, each DataNode runs a block scanner periodically, which verifies the correctness of the data blocks stored in the HDFS.