Data At Rest is one of the Data States for data
The data-centric approach is the encryption of the data itself. Storing passwords is probably the most common known variant of it. But it is also possible to encrypt entire databases or specific records and/or attributes in a database. The focus here is the data it self, and not the File System it is stored on.
There are tons of examples for implementation here to choose from. There is an extensive list of disk encryption software on Wikipedia. When selecting your tool for the job, consider your policy towards Hashing and Encryption. There might be also other corporate policies that state whether you should or should not use open source tools. There is no right or wrong here, other then it is not wise to use software which uses outdated algorithms.