Enabling or disabling delta-sync
The client analyzes the file which is supposed to be transferred and compares the latest version with the previous version. Then it transfers only the changed parts. This feature is called delta sync and makes most sense if you have big files/folders and/or low bandwidth. The client needs to analyze each file, so this feature takes some extra resources (I/O and CPU), but reduces the transfer time.
It is possible to control the use of delta sync separately for LAN and WAN connections.
Delta-sync is turned on by default for LAN and WAN. To enable/disable it:
- Click on Preferences in the main window.
- Click on Expert Settings.
- Configure the checkboxes next to Delta-sync as preferred.
Data integrity check / checksum building when using delta-sync
The client calculates multiple checksums on files that get transferred with or without delta-sync to ensure the data integrity.
- One MD5 checksum is built over the entire file.
- Each transferred file part is also checked with MD5.
- A so called rolling Adler checksum is built to calculate the changed files parts (deltas).
This checksum building ensures that a file is absolutely identically on the source and target computer after transmission.