I'm facing an error when I try to connect to ORACLE server.

I download instant client 12c, which contains basic, sdk, tool, and sqlplus. Now I have the following directories and files. enter image description here

And my envrionment variables are like

## ORACLE Environment
export ORACLE_HOME=${HOME}/instantclient_12_1
export TNS_ADMIN=${HOME}/instantclient_12_1

When I downloaded the client, there was no "tnsnames.ora" file. So, I created it by myself in the "TNS_ADMIN" path. The configuration is such as following.

TEST01 =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.xxx.xxx)(PORT = 1521))
      (SERVICE_NAME = test01)

I checked the HOST value is the server IP address, and port as well. However, when I boot and try to connect to server via sqlplus, it shows like following.

ORA-12545: Connect failed because target host or object does not exist

In the server, it connects very well.. I've tried several solutions from Google, but it won't work..

Thank you.

  • Is this a RAC database? 99% of the ORA-12545 errors I have seen were caused by the lack of name resolution of the VIP addresses on the client. – Balazs Papp May 18 '18 at 6:15
  • No, it's not RAC. The thing I can't figure out is another account is using full client and it can connect to the server. – owcred601 May 18 '18 at 6:28

I solved this problem, but I don't understand the reason.

When I connect to the server from the machine the server is installed on, I can use both following commands:

1. sqlplus server01/server01
2. sqlplus server01/server01@SID

However, from the machine the client is installed on, I can't use the command without @SID. Both envrionments have the same ORACLE_SID environment variable and I specify the SID in "tnsnames.ora".

Could you explain why it works only with @SID?

Thank you.

  • 1
    sqlplus server01/server01 initiates a local connection to a database running on the local machine (unless TWO_TASK is set), but you tried to connect from another machine. – Balazs Papp May 18 '18 at 13:25
  • It sounds like Server side connections are going through memory (IPC I think is the name). This would indicate that your Listener may not be listening for connections on the external ports. – Michael Kutz May 19 '18 at 11:49
  • I tested the case that Balazs let me know in both environments and you are right. Thank you. – owcred601 May 21 '18 at 0:29

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