ORA-27101: shared memory realm does not exist

Hi,

Sometimes You can get “ORA-27101: shared memory realm does not exist ” error.

Details of error are as follows.

ORA-27101: shared memory realm does not exist

This error is related with Invalid ORACLE_HOME and ORACLE_SID or  Database is  really down.

Check your ORACLE_HOME and ORACLE_SID with echo command, or if database is down start it up again as follows.

SQL> startup
ORACLE instance started.
Total System Global Area 1224736768 bytes
Fixed Size 1219112 bytes
Variable Size 167773656 bytes
Database Buffers 1040187392 bytes
Redo Buffers 15556608 bytes
Database mounted.
Database opened.

Do you want to learn Oracle Database for Beginners, then read the following articles.

https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/