Architecture of MapR-DB MapR-DB's architecture gives it a large of advantages over other NoSQL databases. MapR-DB operates directly on the file system MapR-DB tables are implemented directly in the MapR file system (MapR-FS). Tablets are stored in containers in MapR-FS Containers are stored in volumes in MapR-FS MapR provides volumes as a way to organize data and manage cluster performance. A volume is a logical unit that allows you to apply policies to a set of files, directories, and tables. Volumes are used to enforce disk usage limits, set replication levels, define snapshots and mirrors, and establish ownership and accountability.