This document aims to clarify how System Center Data Protection Manager (DPM) handles encrypted and unencrypted files during synchronization.
- If a file has not changed since the last sync, DPM will not transfer any data.
- If a file has changed and is not encrypted with EFS, DPM transfers only the changed blocks of a file.
- If a file has changed and the file is protected with EFS, DPM will transfer the entire file.
The behavior above is by design but it is worth noting that in certain situations this may cause unexpected results if you are not aware of it. For example, let's say you are backing up Outlook PST files that are protected by EFS. Because PST files used by an Outlook client are changing continuously they will therefore be transferred in their entirety at every synchronization. If you have many users with large PST files, this data can consume significantly more network bandwidth and storage space on the DPM server than it would consume if the files were not encrypted.