Corrupt sync with correct file size / mod time (ftp remote, error 450)

I'm trying to understand a possible bug I got but I can't reproduce it anymore, so no logs :frowning:

I was syncing thousands of files to a debian machine with rclone 1.53.3 from a ftp remote (qnap/proftpd) limited to 3 concurrent connections, with rclone sync myftp:folder . --ftp-concurrency 3 -P and I noticed for some files I got ERROR: myfile: Failed to copy: 450 Transfer aborted. Link to file server lost

After it finished I did the sync command again and it showed everything was ok, so it means I got exact file size and mod time for everything, correct?

To be sure files were the same, I generated md5 hashes for all files on the remote machine, compared with my local files, and the files it showed Error 450 didn't match

I used to trust running sync one more time after a "successful" transfer to check, but after this problem I became a little paranoid with hashes, at least for ftp remotes

Does that make sense to anyone? what's the chance of getting exact size / time but different data with rclone?

Thank you

hello and welcome to the forum,

not sure that this is a bug,

  • no log files
  • not reproducible.
  • ftp is an unreliable protocol
  • ftp does not support checksums, so no way to verify file transfer.
  • chance of getting exact size / time but different data. using ftp, should assume that will happen. many posts in the forum about issues with ftp and data corruption.
  • Link to file server lost could mean that there was an issue with the server
  • should be easy to install another file server like sftp which supports checksums. or run rclone serve sftp on the qnap. setup a sftp remote on the dest machine. ask me for details....