KevinG thank you for starting this important topic! I think this discussion will be useful for many users. I will try to split my answer on sections to give in-depth understanding.
Location of Tonfotos database and its backup
Tonfotos stores its internal database on following locations:
- Windows: C:/Users/<UserName>/AppData/Roaming/tonfotos
- macOS: ~/Library/Application Support/tonfotos
This directory stores both database, as well as configuration of Tonfotos (locations of photos, UI settings, etc.)
If you are already using some sort of backup application for your PC, then it typically backs up contents of AppData/Roaming by default, as this is where most of application settings are stored. TimeMachine on Mac does backup ~/Library/Application Support contents automatically.
Faces data location
Information about people on photos is stored in two places: in Tonfotos database, as well as at location of photos themselves in the form of tonfotos.ini files. This solves two problems at the same time:
- If you backup only your photo archive, but do not backup rest of your PC data, all data about faces assigned to people will be saved anyway. In case of PC crash, you will be able to reinstall Tonfotos, and it will pick up information about people from .ini files during initial scan, and you will not need to go thru markup process once again
- In case you store your archive on shared folder or external drive, you can work with this archive from two different PC’s, and information about people on photos will be kept in sync between two (or more) instances of Tonfotos. So you can start working on your PC and (after regular archive rescan) can pick up from there on your MacBook or Linux PC.
As of 0.9.20, albums data is only stored in Tonfotos database.
Tonfotos uses location data which is stored in metadata of photo and video files. It does store in in database too for convenience, but this data is being reconstructed from original files during scan.