2072947 - DB6: First steps for troubleshooting SQL30081N Communication errors

• Short dumps in ST22 showing something like:
  ST22:
  Runtime Errors         DBIF_RSQL_SQL_ERROR
  Exception              CX_SY_OPEN_SQL_DB
  Date and Time        <TIMESTAMP/DATE>

  Short text
  SQL error in the database when accessing a table.

  How to correct the error
  Database error text........: "SQL30081N A communication error has been  detected. Communication protocol being used: "TCP/IP". Communication API being used: "SOCKETS". Location where the error was
  detected: "xxx.xxx.xxx.xxx".  Communication function detecting the error: "recv". Prot"
  Internal call code.........: "[RSQL/READ/<TABNAME>]"
  Please check the entries in the system log (Transaction SM21).

• Entries in the syslog.  SM21 transaction.

  03:11:29 BTC 044 Database error -30081 at CON
  SQL30081N A communication error has been detected.
  Communication protocol being used: "TCP/IP".Communication API being used: "SOCKETS". Location where the error was detected: "xxx.xxx.xxx.xxx". Communication functiondetecting
  the error: "selectForRecvTimeout". Protocol specific error code(s): "10054", "*", "*". SQLSTATE=08001 Database error -30081

• Developer traces: ST11 transaction.

  Entries in dev_wX.log such us:

  C  *** ERROR in DB6Connect[dbdb6.c, 1798] CON = 1 (BEGIN)
  C  &+     DbSlConnectDB6( SQLConnect ): [IBM][CLI Driver] SQL30081N  A communication error has been detected. Communication
  C  &+     protocol being used: "TCP/IP".  Communication API being used:"SOCKETS".  Location where the error was detected: "
  C  &+     xxx.xxx.xxx.xxx".  Communication function detecting the error:
  C  &+     xxx.xxx.xxx.xxx".  Communication function detecting the error: "recv".  Protocol specific error code(s): "10054", "*
  C  &+     ", "0".  SQLSTATE=08001                                                                                          
  C  &+
  C  &+
  C  &+     ABAP location info 'CL_SQL_CONNECTION=============CP', 337
  C  &+
  C  *** ERROR in DB6Connect[dbdb6.c, 1798] (END)
  C  *** ERROR => DbSlConnect to '<SID>' as 'DB2<SID>' failed [dbdb6.c      1811]
  
  CLI0108E  Communication link failure
  severe DB error -99999; work process in reconnect status
  
  

• Db2diag.log. 
  Check the timestamp of the short dump in the db2diag.log.  This is to rule out any issue involving the database or data objects which may report when the SQL30081N, for example
  sql error -30081 performing OPC on table <TABNAME>
  
  
• Database Errors:  Where errors are reported in the db2diag.log for the timestamp of the short dump involving the SQL30081N error .  Collect all the requested logs from KBA  2506601 - ST22 short dumps - What information to send to SAP

• SAP system on IBM Db2 for Linux, UNIX and Windows

SQL30081N, selectForRecvTimeout, "recv", NUM_LOG_SPAN, diagnostics, TCP/IP, Client termination, CLI, 9999, detected, interface, location, client, application, severe DB error -99999; work process in reconnect status, CLI0108E  Communication link failure. , KBA , BC-DB-DB6 , DB2 Universal Database for Unix / NT , How To