As a database moves from the shutdown stage to being fully open, it
performs internal consistency checks with the following stages:
•
NOMOUNT: For an
instance to reach the NOMOUNT (also known as STARTED) status, the instance must
read the initialization parameter file. No database files are checked while the
instance enters the NOMOUNT state.
•
MOUNT: As the
instance moves to the MOUNT status, it checks whether all control files listed
in the initialization parameter file are present and synchronized. If even one
control file is missing or corrupt, the instance returns an error (noting the
missing control file) to the administrator and remains in the NOMOUNT state.
•
OPEN: When the
instance moves from the MOUNT state to the OPEN state, it does the following:
Checks whether all redo log groups known to the control file have at
least one member present. Any missing members are noted in the alert log.
