Resuming interrupted backups

[rdinse]

The --partial option could perhaps be used to easily implement resumption.

--partial By default, rsync will delete any partially transferred file if the transfer
         is interrupted. In some circumstances it is more desirable to keep partially
         transferred files. Using the --partial option tells rsync to keep the partial
         file which should make a subsequent transfer of the rest of the file much faster.

https://unix.stackexchange.com/a/252969/122623

[KayTaneJupiter]

Also --append-verify