Thanks. GlassWire logs network activity so it will always have to write data.
We are working on an update that will not write host/traffic type info as an option so people like yourself won't have to use your hard drive. Without logging hosts and traffic types GlassWire won't have to write much.
Meanwhile you can also switch to "Incognito" mode and just use GlassWire as a firewall if you don't want to log anything, or you can move your database to another HD.
Open the C:\ProgramData\glasswire\service\ folder;
Create the file glasswire.conf
Add this string to the glasswire.conf:db_file_path=d:\glasswire.db
Instead of the “D:\glasswire.db” you can set any other path, which is preferable for you. Now if you restart the service, the new database will be created at d:\glasswire.db.
The previous database will be kept at the C:\ProgramData\glasswire\service\glasswire.db. Also you may stop the service, move the C:\ProgramData\glasswire\service\glasswire.db to D:\glasswire.db, and start the service.
In that case Glasswire will continue to work with the previous database.
The service may be stopped and started at the task manager’s “Services” tab or at the Windows Service manager.