De man rsync
The read-batch option expects the destination tree that it is updating to be identical to the destination tree that was used to create the batch update fileset. When a differ-
ence between the destination trees is encountered the update might be discarded with a warning (if the file appears to be up-to-date already) or the file-update may be attempted
and then, if the file fails to verify, the update discarded with an error. This means that it should be safe to re-run a read-batch operation if the command got interrupted. If you wish to force the batched-update to always be attempted regardless of the file's size and date, use the -I option (when reading the batch). If an error occurs, the destina- tion tree will probably be in a partially updated state. In that case, rsync can be used in its regular (non-batch) mode of operation to fix up the destination tree.