Pixometry exports a backup of the database automatically once a day and every time a change is made to channel settings. These files are stored in either: 

../Pixometry/cluster/preferences

(Single server)

Or if you run multiple Pixometry instances in multi-server (cluster): 

<cluster network volume>/preferences

The files are named "ClaroDatabaseBackup.dmp" with added number or date. 

It makes sense to backup this folder regularly. 

To restore the database from one of these backup files: 

Choose the most recent backup file

Close the user-interface if it is still open. In the Windows Services control panel, locate the "Pixometry" service and stop it. On MacOS, use the  stop_claro.command script in the ../Pixometry/commands folder. 

delete (or rename or move) these folders from the Pixometry installation directory: "arjuna_store" and "database_data". 

Copy the ClaroDatabaseBackup.dmp file to ../Pixometry/DatabaseImport

Restart the Pixometry service. 

It will take a bit longer, depending on how large your preferences are, to start up Pixometry completely and you are able to start and connect the UI again. Do not interrupt this process.