-- Oracle 12c Grid Infrastructure Management Repository MGMTDB --

After installing Oracle 12c Grid Infrastructure on an ODA X3-2 we started getting a warning from Enterprise Manager alerting us that the target MGMTDB Database SYSMGMTDATA tablespace is 85% full. As you can imagine we were surprised as we did not recognize that database. We reached out to few people before and realized that this must be something new.

Starting 12.1.0.2 Oracle creates a new mandatory database called MGMTDB, Oracle creates on it Cluster Health Monitoring (CHM) Data among others, this database gets failover to a surviving node in case one node goes down, the database needs to be up and running, it starts up automatically.

Please note: There is a minus sign in from of the database name

Database name: -MGMTDB
ORACLE_HOME: Same as the GRID_HOME

I am not sure about the password for SYS or SYSTEM on it, but you can connect as sysdba

There are 3 tablespaces on it (UNDO, SYSTEM and SYSAUX) , you do not have to worry about space management since the datafiles are auto-extensible.

MOS 2065175.1 contains information about how to use MDBUtil tool, this tool allows you to perform a variety of operations with the management repository. The best article I found with information related to this topic is from Amit Bansai and you can access it on this link.