If you get this error, check the alert file, most likely there is not enough space on your recovery area to create an archivelog; and if your problem is archivelog, clean the area and start the database again.
SQL> connect / as sysdba
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
Total System Global Area 1987563520 bytes
Fixed Size 2214696 bytes
Variable Size 1040188632 bytes
Database Buffers 939524096 bytes
Redo Buffers 5636096 bytes
Database mounted.
ORA-03113: end-of-file on communication channel
Process ID: 5114
Session ID: 191 Serial number: 3
How to fix the problem:
On the RMAN tool, delete archivelog older than a week.
# rman target /
RMAN> startup mount;
RMAN> delete archivelog until time “sysdate-7″;
or
RMAN> delete force archivelog all;
or
RMAN> delete backup completed before “sysdate-3″;
