inefficient: --checksum calculation shouldn't be done for new files

Carlos Carvalho carlos at
Sun Jul 3 18:12:48 MDT 2011

Jamie Lokier (jamie at wrote on 4 July 2011 00:00:
 >Carlos Carvalho wrote:
 >> When --checksum is used they're calculated in both ends to see if the
 >> file should be transfered. This is of course not necessary if the file
 >> doesn't exist in the destination. However, the checksum is still
 >> calculated by the sender, which is often a very large overhead.
 >> Would it be possible to avoid it?
 >Doesn't the receiver use the checksum to verify it received the file
 >with no errors?

Yes, but this always happens, not only with -c. That checksum is
calculated during the download and has no overhead. The one with -c is
done before, just to decide whether to download.

More information about the rsync mailing list