Arguably, encryption is the best form of protection for data at rest—it's certainly one of the best. 

You can encrypt files that will be at rest either before storing them or by encrypting the entirety of a given storage drive or device. 

https://www.teradata.com/Trends/Data-Management/Data-at-Rest#:~:text=Arguably%2C%20encryption%20is%20the%20best,given%20storage%20drive%20or%20device.