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TNS-12547: TNS:lost contact

Hi,

Sometimes You can get “TNS-12547: TNS:lost contact  ” error.

 

Details of error are as follows.

TNS-12547: TNS:lost contact
Cause: Partner has unexpectedly gone away, usually during process startup.
Action: Investigate partner application for abnormal termination. On an Interchange, this can happen
if the machine is overloaded.

 

 

To solve this problem, firstly check sqlnet.ora file.

[oracle@MehmetSalih PRELIVE_MehmetSalih]$ cat sqlnet.ora
###############################################################
#
# Do not edit settings in this file manually. They are managed
# automatically and will be overwritten when AutoConfig runs.
# For more information about AutoConfig, refer to the Oracle
# E-Business Suite Setup Guide.
#
#$Header: NetServiceHandler.java 120.28.12020000.2 2012/07/05 11:52:15 brayasam ship $
#
###############################################################

NAMES.DIRECTORY_PATH=(TNSNAMES, ONAMES, HOSTNAME)
SQLNET.EXPIRE_TIME= 10
tcp.validnode_checking = yes
tcp.invited_nodes=(MehmetSalih.Deveci.local)
SQLNET.INBOUND_CONNECT_TIMEOUT =60


IFILE=/data/oracle/PRELIVE/12.1.0/network/admin/PRELIVE_MehmetSalih/sqlnet_ifile.ora
[oracle@MehmetSalih PRELIVE_MehmetSalih]$

 

You should remove tcp.validnode_checking = yes and tcp.invited_nodes=(MehmetSalih.Deveci.local) entries.

[oracle@MehmetSalih PRELIVE_MehmetSalih]$ vi sqlnet.ora
[oracle@MehmetSalih PRELIVE_MehmetSalih]$
[oracle@MehmetSalih PRELIVE_MehmetSalih]$



After remove related parameters, sqlnet.ora file should be like following.


[oracle@MehmetSalih PRELIVE_MehmetSalih]$ cat sqlnet.ora
###############################################################
#
# Do not edit settings in this file manually. They are managed
# automatically and will be overwritten when AutoConfig runs.
# For more information about AutoConfig, refer to the Oracle
# E-Business Suite Setup Guide.
#
#$Header: NetServiceHandler.java 120.28.12020000.2 2012/07/05 11:52:15 brayasam ship $
#
###############################################################

NAMES.DIRECTORY_PATH=(TNSNAMES, ONAMES, HOSTNAME)
SQLNET.EXPIRE_TIME= 10
SQLNET.INBOUND_CONNECT_TIMEOUT =60


IFILE=/data/oracle/PRELIVE/12.1.0/network/admin/PRELIVE_MehmetSalih/sqlnet_ifile.ora
[oracle@MehmetSalih PRELIVE_MehmetSalih]$

 

Now reload or stop start Listener. Login database via sqlplus or Toad like following.

 

Problem has been solved.

[oracle@MehmetSalih ~]$ sqlplus mehmet/mehmet@PRELIVE

SQL*Plus: Release 12.1.0.2.0 Production on Thu Aug 1 16:33:34 2019

Copyright (c) 1982, 2014, Oracle. All rights reserved.

Last Successful login time: Thu Aug 01 2019 17:24:06 +03:00

Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

 

Sometimes oracle.exe or oracle executable file’s permission may be modified

Check oracle like following.

[oracle@MehmetSalih ~]$ cd $ORACLE_HOME/bin
[oracle@MehmetSalih bin] $ ls -ltr oracle
[oracle@MehmetSalih bin] $ -rwx-xr-x 1 oracle oinstall 136803483 Jul 16 10:24 oracle

 

Change permissions and give 6751 permission as below:

[oracle@MehmetSalih bin] $ chmod 6751 oracle
[oracle@MehmetSalih bin] $ ls -ltr oracle
-rwsr-s--x 1 oracle oinstall 136803483 Jul 16 10:24 oracle

 

 

Do you want to learn more details about RMAN, then read the following articles.

https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/

 

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