I. Log into infrastructure instance & login as sysdba;
bash-3.00$ sqlplus /nolog
SQL> conn / as sysdba;
SQL> select status from v$instance;
STATUS
------------------------------------
OPEN
II. Log into infrastructure instance & issue the following command
bash-3.00$ ps -ef | grep pmon
ocsinfra 11021 1 0 09:15:15 ? 0:09 ora_pmon_orcl
ocsinfra 17960 17592 0 10:47:15 pts/2 0:00 grep pmon
If DB instance is running, then the above command returns the pmon process running
