Cannot Start Oracle Database after Shutdown

The aim when shutting down for maintenance (or cold backup) is that the database is left in a consistent state with no need for rollback/recovery on startup.

There are 3 SQL*Plus shutdown commands that achieve this in theory, all of which immediately prevent new sessions connecting to the instance:

1. shutdown normal or just shutdown: waits for all sessions to disconnect. This mode is rarely used in practice because it relies on well-behaved clients not leaving connections open. This used to be the only shutdown mode that did not cancel running transactions.
2. shutdown transactional: disconnects sessions once currently running transactions complete, preventing new transactions from beginning.
3. shutdown immediate: disconnects all sessions immedately and rolls back interrupted transactions before shutting down. Note that the disconnections are immediate, but the shutdown may not be as any interrupted transactions may take time to roll back.

The fourth mode of shutdown is shutdown abort. This is like pulling the power cord - the instance stops now without any cleanup. You usually want to bring the database up again afterwards and shut down cleanly immediately afterwards as in your example. The concepts guide says:

This mode is intended for emergency situations, such as when no other form of shutdown is successful.

All the examples you give perform a checkpoint as part of the shutdown [normal] or shutdown immediate so explicit checkpointing is presumably to reduce the time required for recovery.

general advice:

• Do not use shutdown normal.
• Use shutdown transactional for attended shutdown only, when you want to minimise cancelled transactions (attended only because this kind of shutdown is not guaranteed to shut the database down at all if timeouts are breached).
• Use shutdown immediate for unattended shutdown or when you do not care about currently running transactions.
• Do not use shutdown abort (plus startup/shutdown) unless you have to - this was more common in much earlier versions of Oracle that it is today. In other situations (not patch/upgrade), if you have a need to minimise downtime this mode may be appropriate.

You can use the dbstart/dbshut scripts which come with an Oracle install. They are available under $ORACLE_HOME/bin.

After a fresh install you have to edit the /etc/oratab file:

# cat /etc/oratab
# format: $ORACLE_SID:$ORACLE_HOME:N|Y
my_sid:/home/juser/app/juser/product/11.2.0/dbhome_1:N
# sed -i 's/:N$/:Y/' /etc/oratab
# grep my_sid /etc/oratab
my_sid:/home/juser/app/juser/product/11.2.0/dbhome_1:Y

Then you can use the scripts like this:

$ whoami
juser
$ dbstart $ORACLE_HOME
$ # execute DB jobs ...
$ dbshut $ORACLE_HOME

dbstart brings all up which is needed for Pro*C/OCI programs.

Using dbstart/dbshut is an improvement above the custom method mentioned in the question:

method                time    called tools
―――――――――――――――――――――――――――――――――――――――――――――――――――――
dbstart              5.7 s    lsnrctl, sqlplus
dbshut               5.7 s    lsnrctl, sqlplus
custom startup      27.9 s    lsnrctl, sqlplus, emctl
custom shutdown     31.0 s    lsnrctl, sqlplus, emctl

(times on a Core i7/2.8GHz system, slow spinning hard disk.)

How dbstart/dbshut work

A dbstart $ORACLE_HOME$ call is basically equivalent to:

$ lsnrctl start
$ echo -e 'connect / as sysdba\nstartup\nquit'| sqlplus /nolog

And a dbshut $ORACLE_HOME$ is basically equivalent to:

$ lsnrctl stop
$ echo -e 'connect / as sysdba\nshutdown\nquit'| sqlplus /nolog

(you can verify if everything is shutdown via ps aux | grep 'tnsl\|ora')

Note that the order of the commands is important. That means when lsnrctl start is executed after the sqlplus-startup command then the Pro*C/OCI program still complains about an unavailable TNS-listener.

And this is exactly the problem with the command sequence in the question - where the emctl start just workarounds the wrong order because it fixes the TNS-listener setup part.

Also note that for executing Pro*C/OCI programs the EMCTL service is not needed.