Applies To:
Oracle database-enterprise edition-version 10.2.0.1 to 12.1.0.2 [Release 10.2 to 12.1]
Information in this document applies to any platform.
Checked for relevance on 21-jul-2017***
GOAL
Show A-from connect to a database through Sqlplus if all other connection methods is hanging. Using a Sqlplus preliminary connection you'll be able to connect to the database since no session is actually created, b UT you'll have limited access to the SGA. This would help in capturing diagnostic information like a systemstate dump to aid in problem resolution.
Solution
There is ways to connect to Sqlplus using a preliminary connection.
Sqlplus-prelim/as SYSDBA
Sqlplus/nolog
Set _prelim on
Connect/as SYSDBA
For example:
Sql> set _prelim on
Sql> Connect/as SYSDBA
Prelim Connection established
REFERENCES
note:61552.1 -Oracle 9i and below:exhaustive troubleshooting Steps for Oracle Database hanging issues
How to connect Using A Sqlplus Preliminary Connect