Hi,
Sometimes you can get ” ORA-01081: cannot start already-running ORACLE – shut it down first ” error.
Details of error are as follows.
SQL> startup
ORA-01081: cannot start already-running ORACLE - shut it down first
This errors means Oracle Instance is already opened, so you should make sure Oracle SID and Oracle Home.
Check the Oracle SID and Oracle Home, if they are Ok or not ?
[oracle@MSDBdbadm01:/home/oracle:> echo $ORACLE_SID [oracle@MSDBdbadm01:/home/oracle:> echo $ORACLE_HOME
Compare Oracle SID and Oracle home from oratab file. oratab files are exist under the following paths.
/etc/oratab /var/opt/oracle/oratab
If they are not set correctly, then set them as follows.
Unix/Linux :
[oracle@MSDBdbadm01:/home/oracle:> ORACLE_SID=INSTANCE_NAME [oracle@MSDBdbadm01:/home/oracle:> export ORACLE_SID [oracle@MSDBdbadm01:/home/oracle:> export ORACLE_HOME=/u01/app/product/12.2.0/dbhome_1 [oracle@MSDBdbadm01:/home/oracle:> sqlplus / as sysdba
Or shutdown abort the Instance then start it up again as follows.
SQL> startup ORACLE instance started. Total System Global Area 188743680 bytes Fixed Size 1218412 bytes Variable Size 67111060 bytes Database Buffers 113246208 bytes Redo Buffers 7168000 bytes Database mounted. Database opened. SQL>
Oracle Home and Oracle SID must set properly every time.
Do you want to learn Oracle Database for Beginners, then read the following articles.
https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/