This post will explain Content Defined Chunking (CDC) and how it is used by restic.
Backup programs need to deal with large volumes of changing data. Saving the whole copy of each file again to the backup location when a subsequent (usually called “incremental”) backup is created is not efficient. Over time, different strategies have emerged to handle data in such a case.
This is a companion discussion topic for the original entry at https://restic.net/blog/2015-09-12/restic-foundation1-cdc