Error during Datasync Transfer

Hi, from Datasync FAQ:

https://aws.amazon.com/datasync/faqs/

Q: What happens if an AWS DataSync task is interrupted?

A: If a task is interrupted, for instance, if the network connection 
goes down or the AWS DataSync agent is restarted, the next run 
of the task will transfer missing files, and the data will be complete 
and consistent at the end of this run. Each time a task is started it performs 
an incremental copy, transferring only the changes from the source to 
the destination.

So, as expected only missing or updates files will be transferred when you restart datasync

Hope it helps! Didier