@hibrid0, that's a good idea and it's the only thing that has saved my butt in the past without having to redo everything from scratch.
To answer your question, it's wherever the Resilio Sync software runs from. I know that's a generic answer but it can change depending on how you're running Resilio Sync (i.e. Windows interactively vs Windows as a service vs on a Mac).
On Windows interactively (you see the Resilio Sync icon in your system tray), the files are in %APPDATA%\Resilio Sync (hold Windows Key and press "R" type in "%APPDATA%\Resilio Sync" and it should come up)
On Windows as a service (Resilio Sync is running even at the CTRL+ALT+DEL screen), it's in "C:\Users\[whatever_the_service_account_name_is]\AppData\Roaming\Resilio Sync".
When in doubt, open up a command prompt with admin rights and just type "c:" then "cd\" then "dir sync.dat /s/a/p" and it should find the file and reveal its path.
I don't know where it is on a Mac because I generally don't use Macs. However, the same principle applies. Instead of a command prompt, you should be able to open up a terminal window and type in "find / -name sync.dat" and it should locate the file.