How to check data integrity?

Question

linux

Hello! Faced the problem of checking the integrity of the data.
Given: a ~1tb file was copied, a snapshot of the hard disk, I tried to remove the md5 hash sum, but the result of the utility 's operation md5sum -b hdd.imgon the same machine is always different.
how to check file integrity.
The SystemRescueCd-x86-4.6.1 distribution is based on Gentoo

Answer 1

You need to use the normal hash implementation and use it correctly. MD5 does not contain any elements of randomness and the hash for the same data must be the same.

Answer 2

If you don’t touch this file while md5sum is running (and you never know if the file systems from it are mounted somewhere), but the hash differs from run to run, then you have a problem with your system. For example, the drive cannot correctly read a certain area and returns garbage instead. Or a memory problem.

Answer 3

As practice shows - md5sum is not mistaken. Look for a problem with a file or with a piece of iron.
We have one pebble md5sum incorrectly counted, and then 10/2 it became 3 in production;)