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ORA-00020: maximum number of processes This error occurs when your total numbers of sessions connecting to oracle database has exceeded the max limit set in parameter file. Simplest way to overcome this error is to reset the max sessions value to a greater value than existing.Here is how to do it   oracle@LINUX201:[~] $ sqlplus / as sysdba SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:20:26 2016 Copyright (c) 1982, 2013, Oracle.  All rights reserved. ERROR: ORA-00020: maximum number of processes (500) exceeded oracle@LINUX201:[~] $ sqlplus / as sysdba SQL*Plus: Release 11.2.0.4.0 Production on Mon Jun 13 10:23:42 2016 Copyright (c) 1982, 2013, Oracle.  All rights reserved. ERROR: ORA-00020: maximum number of processes (500) exceeded Enter user-name: Disconnected from ORACLE I wasn't able get into the oracle database to kill some database session. So I tried to kill few sessions on OS to make my way into DB. oracle@LINUX201:[~] $ ps -ef|grep oracle . . . . . . ....

Question:   I get this error when starting my Oracle database.  What is the ORA-01113 error? SQL> ALTER TABLESPACE sample  ONLINE  2  ; ALTER TABLESPACE sample * ERROR at line 1: ORA-01113: file 27 needs media recovery ORA-01110: data file 27: '/u02/oracle/oradata/ORCL/sample.dbf' SQL> recover datafile '/u02/oracle/oradata/ORCL/sample.dbf'; Media recovery complete. SQL> ALTER TABLESPACE sample ONLINE; ALTER TABLESPACE sample ONLINE * ERROR at line 1: ORA-01113: file 29 needs media recovery ORA-01110: data file 29: '/u02/oracle/oradata/ORCL/SAMPLE10.dbf' SQL> recover datafile '/u02/oracle/oradata/ORCL/SAMPLE10.dbf'; Media recovery complete. SQL> ALTER TABLESPACE sample ONLINE; ALTER TABLESPACE sample ONLINE * ERROR at line 1: ORA-01113: file 30 needs media recovery ORA-01110: data file 30: '/u01/app/QPDEV/SAMPLE11.dbf' SQL> recover datafile '/u01/app/QPDEV/SAMPLE11.dbf'; Media recovery complete. SQL> ALTER TABLESPACE s...