As noted in the system requirements page here Rapidminer server requires an operational database for its own purposes.
Rapidminer server supports following database for its operational database
Microsoft SQL Server
Do I need to update the database server directly
On a normal usage there should be no need to udpate the Rapidminer server database directly. Infact it is hihgly recommended that one should not interfere by doing any sort of modification directly on the database server.
What is the database used for
The operatonal database is used for maintaining several critical information and settings used by Rapidminer server. Some examples of what these settings include are as following
Repository items (These are your process, models, data(Examplesets) that are stored under Rapidminer server repository.
User and groups information
LDAP configuration related settings
Rapidminer server Apps configuration
Configuration and setting for Rapidminer server process exposed as web services
Connection information to different database and cloud providers
Actual data that is stored on Rapidminer server repository using the store operator
Logs for various items generated during server lifetime
What is the expected size
Most of the items stored by Rapidminer server are very small in nature, however if the users save data using the "store" operator then the size can grow dramatically based on the size of the data that is stored. Please also note that when Rapidminer "stores" data in its repository it also adds more metadata around it, thereby increasing the storage size.
Should I be backing up the database
Yes absolutely. the database contains lots of critical information and can act as a good resource to restore the environment to a previously known stable state. It is highly recommended to take backups regularly and special backups should be planned and taken before upgrades or major changes are planned to the system