I've used a command similar to this to
rsync files from macOS to Linux:
rsync -avz <ip-address>:/Backup/ Backup/
Backup/ was previously copied from the same machine using
scp, with no files changed. I thought that
rsync would be a noop, but it started to overwrite all files (probably, because of different timestamps), causing a lot of disk writes. I've tried the same command with
--size-only and it finished almost instantly. Does
rsync completely overwrite the files that have different timestamps (i.e. not checking the difference)? Does it depend on the size of the files?