Connection limit - ORA-28547

Question

I created test oracle server 11.2.0.1.0 on virtualbox.
I enable shared_server configuration as per the document.
With the tnsnames entry "(SERVER = SHARED)", I can connect to the server using the service name. The v$session shows the 'server' column as shared. Everything works fine so far.
I have client server application which connects to database server. Itermittently i see error in application log
ORA-28547: connection to server failed, probable Oracle Net admin errorSo i manually tested launching sqlplus connections. I can see 20 shared server connections can be created(V$session.server column). When I launch 21st sqlplus connection it gives ORA-28547.
Parameters are set as below:
sessions is set to 400
shared_server_sessions is set to 300
circuits is default i.e not set (as suggested in the docs to avoid limiting virtual circuits)
I can see the shared server configuration working but unable to figure out why there is a limit of 20 shared server connections. Any tips will be helpful.
Thanks

Answer 1

Listing below the information. Using netca I re-created the listener.ora, tnsnames.ora and sqlnet.ora. Retested - started sqlplus sessions: 20 go though without errors, 21st returned ORA-28547; Checking v$session shows 'SERVER' listed as 'SHARED' for 20 sessions.
1.Is it standard edition or Enterprise Edition, kindly post also select * from v$version.
SQL> select * from v$version
  2  ;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Solaris: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production2.show parameter shared_servers and MAX_SHARED_SERVERS
SQL> show parameters shared_servers
NAME                                 TYPE        VALUE
max_shared_servers                   integer     20
shared_servers                       integer     13.I asked you :
7.What if you drop and recreate listener and tnsnames.ora with netca utility.
I re-created the listener now as suggested using netca -
oracle@sol01:~$ lsnrctl stop LISTENER_DB01
LSNRCTL for Solaris: Version 11.2.0.1.0 - Production on 10-JUN-2012 19:04:34
Copyright (c) 1991, 2009, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=sol01)(PORT=1521)))
The command completed successfullyRecreating using netca - the gui pops up, below is the log from actual session where netca was run and followup file check, listener check was done.
oracle@sol01:~$ netca
Oracle Net Services Configuration:
Configuring Listener:LISTENER_DB01
Listener configuration complete.
Oracle Net Listener Startup:
    Running Listener Control:
      /u01/DB01/product/11.2.0/dbhome_1/bin/lsnrctl start LISTENER_DB01
    Listener Control complete.
    Listener started successfully.
Profile configuration complete.
Default local naming configuration complete.
    Created net service name: DB01
Oracle Net Services configuration successful. The exit code is 0
oracle@sol01:~$ ls -ltr $ORACLE_HOME/network/admin
total 15
-rw-r--r--   1 oracle        dba     187 May  8  2007 shrept.lst
drwxr-xr-x   2 oracle        dba       5 Jun  8 19:15 samples
-rw-r--r--   1 oracle        dba     396 Jun  9 12:21 listener.ora.bak
-rw-r--r--   1 oracle        dba     396 Jun  9 12:21 sqlnet.ora.bak
-rw-r--r--   1 oracle        dba     334 Jun  9 12:23 tnsnames.ora.bak
-rw-r--r--   1 oracle        dba     396 Jun 10 19:27 listener.ora
-rw-r--r--   1 oracle        dba     226 Jun 10 19:27 sqlnet.ora
-rw-r--r--   1 oracle        dba     334 Jun 10 19:28 tnsnames.ora
oracle@sol01:~$ cat $ORACLE_HOME/network/admin/listener.ora
# listener.ora Network Configuration File: /u01/DB01/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
LISTENER_DB01 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = sol01)(PORT = 1521))
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
ADR_BASE_LISTENER_DB01 = /u01/DB01
oracle@sol01:~$ cat $ORACLE_HOME/network/admin/tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/DB01/product/11.2.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.
DB01 =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = sol01)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = DB01)
oracle@sol01:~$ cat $ORACLE_HOME/network/admin/sqlnet.ora
# sqlnet.ora Network Configuration File: /u01/DB01/product/11.2.0/dbhome_1/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (TNSNAMES)
ADR_BASE = /u01/DB01
oracle@sol01:~$
oracle@sol01:~$ lsnrctl status LISTENER_DB01
LSNRCTL for Solaris: Version 11.2.0.1.0 - Production on 10-JUN-2012 19:41:37
Copyright (c) 1991, 2009, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=sol01)(PORT=1521)))
STATUS of the LISTENER
Alias                     LISTENER_DB01
Version                   TNSLSNR for Solaris: Version 11.2.0.1.0 - Production
Start Date                10-JUN-2012 19:27:20
Uptime                    0 days 0 hr. 14 min. 17 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/DB01/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File         /u01/DB01/diag/tnslsnr/sol01/listener_DB01/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=sol01)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
Services Summary...
Service "DB01" has 1 instance(s).
  Instance "DB01", status READY, has 2 handler(s) for this service...
The command completed successfully
oracle@sol01:~$