These .dat files contain updates that were not inserted into the database due to a disconnection between the gateway and the database. They will be inserted into the database once the connection is re-established.
We advise against deleting these files unless you are certain that you no longer need this data. Before taking any action, ensure to check the connectivity between the gateway and the database to prevent the creation of these files.
Once the connection is restored, the Gateway will re-read any dump files and attempt to insert the data into the database. If there are no further issues with the database, these files should automatically be removed after the data has been successfully inserted.
Alternatively, you can temporarily move the files to another location and manually insert the data at a convenient time using the Gateway command line option -process-dump-files. You can find more details about this process in the documentation provided in this link.
Geneos - Gateway - Gateway database logging, performance and .dat dump files
Be aware that if you delete these files, the data stored within them will be lost permanently, and you will not be able to recover them.