TNS-12518: TNS:listener could not hand off client connection

비정상적인 접속장애 발생..
리스너 로그 파일을 확인해보니 아래 첫번째 에러로그가 남아 있네요.

오라클 엔지니어에게 점검 요청을 하였는데 현재는 정상적이라고만 하고,,
답답해서 구글을 뒤져봐도 관련 웹글 흔적도 없고,,,
뭐 혹시나 하는 마음에 메타링크에서 관련 에러 메시지를 찾아보니 단번에 나와버렸습니다. (--)

지난 2008년 12월 메타링크에서 이미 보고된 내용이며,,
원인 및 조치방법에 대해 아래와 같이 간결하게 안내되어 있네요..(너무 간결한듯..)  
서버 운영 환경하고 오라클 메모리 관련 환경 parameter 하고 궁합이 안맞는듯 하지만,,
뭐.. H/W, 오라클 엔지니어를 통해 확인 해봐야 자세한 원인을 알 수 있을 듯 합니다.




출처: 오라클 메타링크


Error: 12: Not enough space

 TNS-12518: TNS:listener could not hand off client connection
   TNS-12549: TNS:operating system resource quota exceeded
     TNS-12560: TNS:protocol adapter error
       TNS-00519: Operating system resource quota exceeded
         IBM/AIX RISC System/6000 Error: 12: Not enough space

Cause:
This is a memory related issue. The error indicates that there is not enough memory available to spawn and hand off the client connections.
Typical problems are:
- Out of system memory / swap
- Out of process slots in the process table
- Streams resources depleted
- Out of File Handles
- sga memory usage

Action:
1. Check in the alert log for any possible memory related error.
2. Increase swap/Virtual memory if possible the available memory.
3. SGA and PGA can be reduced to address the memory consumption.
4. MTS mode can be used to reduce the amount of process and memory consumption.

Error: 32: Broken pipe

TNS-12518: TNS:listener could not hand off client connection
 TNS-12547: TNS:lost contact
   TNS-12560: TNS:protocol adapter error
     TNS-00517: Lost contact
       IBM/AIX RISC System/6000 Error: 32: Broken pipe

Cause:
The error 32 indicates the communication has been broken while the listener is trying to hand off the client connection to the server process or dispatcher process.

Action:
1.  One of reason would be processes parameter being low, and can be verified by the v$resource_limit view.
2. In Shared Server mode, check the 'lsnrctl services' output and see if the dispatcher has refused any connections, if so, then consider increasing the number of dispatchers.
3. Check the alert log for any possible errors.
4. Memory resource is also another cause for this issue. Check the swap, memory usage of the OS.