Simple questions, I hope. if I'm running checksum (as a -c flag) on rsync, like so -

rsync -c --log-file="/location/logfile.txt" \
    -e "ssh -p {port number}" {source} {destination}
  1. will detected differences in hashes/values show up in the logfile? And how would they be indicated - .c....? Everything I've been reading about rsync logfiles doesn't seem to mention checksum. If human-readable checksum output won't show up on the logfile, how do I generate that output?

  2. Is this checksum comparing files from source against destination? Also, is it important to do that, or is it just as useful to run checksums on successive copies of my files on the destination server? Another way of asking this might be - is there a significant risk of file alteration or corruption as a result of the rsync run itself?

  3. If all I'm doing is transferring static content - e.g. PDFs, image files, text files and the like - no executable files, no ISO's nothing like that - is checksum really even necessary?

Those are all my questions! Thanks everyone.


Checksums are needed only if there is a risk that something manipulates the mtime values i.e. writes to a file and then sets back the file mtime to the earlier value.

In such a situation I would consider using btrfs snapshots and snapshot transfers instead. That is very efficient because similar to rsync it transfers only the changed data but it need not compare the two sides because it knows from the snapshot what has been changed.

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