I set up a NanoPi Neo 2 with OpenMediaVault (Debian Jessie) as its OS and have an hdd attached to it (the OS is on an SD card).
When I now copy my data from my external hard drive onto my system with
rsync -avP --checksum [source] [dest] and check back if everything went well with
diff -r [source] [dest], it still tells me that some files differ.
That happens even after repeating the procedure several times and even if I delete the differing files according to diff and resyncing everything.
So my question is: is this a normal behaviour and nothing to worry about or is my (new) hard drive on the system somehow faulty and therefore the new files get corrupted quickly after (hopefully correct) transfer with rsync?