Tried to connect to the database, but it failed with ORA-01033 like the following.
SQL> conn hr/hr@orcl
ORA-01033: ORACLE initialization or shutdown in progress
Process ID: 0
Session ID: 0 Serial number: 0
ORA-01033 means that the database you want to connect is in MOUNT state currently, it might encouter some difficulties to be open. If the error message surprised you, you should check the alert log of the database for further investigation.
With little chances, it's about to go up or down. The most chances are, the instance stays still in MOUNT state without doing anything, it's not going up or down, so don't be fooled by the error message.
To solve ORA-01033, we can notify DBA to open the database for public to access. If the database cannot be open at this moment, you can still connect to it as long as you are a SYSDBA.
To open the database from MOUNT state, we can either open it in 1 step:
SQL> alter database open;
Now the database is open, it may be far behind the instance startup. In fact, there's difference between instance startup time and database open time.
Or restart it in 2 steps.
SQL> shutdown immediate
If this is in a shutdown, the database might have some troubles to shutdown.
Of course, if the database is really in starting up or shutting down, you have to wait for the progress to be completed.