Tuning Solaris systems

• Description: Specifies the maximum number of open files supported. If the value of this parameter is too low, a Too many files open error is displayed in the WebSphere Application Server stderr.log file.
• How to view or set: Check the UNIX reference pages on the file descriptor limits for parameters and commands used. For the KornShell (ksh), the ulimit -n command can be used to set the desired file descriptor value and the ulimit -a command to display all current ulimit settings in place.
• Default value: 1024
• Recommended value: 10000

• Description: Notifies TCP/IP on how long to keep the connection control blocks closed. After the applications complete the TCP/IP connection, the control blocks are kept for the specified time. When high connection rates occur, a large backlog of the TCP/IP connections accumulates and can slow server performance. The server can stall during certain peak periods. If the server stalls, the netstat command shows that many of the sockets that are opened to the HTTP server are in the CLOSE_WAIT or FIN_WAIT_2 state. Visible delays can occur for up to four minutes, during which time the server does not send any responses, but CPU utilization stays high, with all of the activities in system processes.
• How to view or set: Use the get command to determine the current interval and the set command to specify an interval of 30 seconds. For example:

  ndd -get /dev/tcp tcp_time_wait_interval     
  ndd -set /dev/tcp tcp_time_wait_interval 30000

• Default value: The default time wait interval for a Solaris operating system is 240000 milliseconds, which is equal to 4 minutes.
• Recommended value: 60000 milliseconds

• Description: Specifies the timer interval prohibiting a connection in the FIN_WAIT_2 state to remain in that state. When high connection rates occur, a large backlog of TCP/IP connections accumulates and can slow server performance. The server can stall during peak periods. If the server stalls, using the netstat command shows that many of the sockets opened to the HTTP server are in the CLOSE_WAIT or FIN_WAIT_2 state. Visible delays can occur for up to four minutes, during which time the server does not send any responses, but CPU utilization stays high, with all of the activity in system processes.
• How to view and set: Use the get command to determine the current interval and the set command to specify an interval of 67.5 seconds. For example,

  ndd -get /dev/tcp tcp_fin_wait_2_flush_interval
  ndd -set /dev/tcp tcp_fin_wait_2_flush_interval 67500

• Default value: 675000 milliseconds
• Recommended value: 67500 milliseconds

• Description: The keepAlive packet ensures that a connection stays in an active and established state.
• How to view or set: Use the ndd command to determine the current value or to set the value. For example:

  ndd -set /dev/tcp tcp_keepalive_interval 300000 

• Default value: 7200000 milliseconds
• Recommended value: 15000 milliseconds

• Description: An entry in the /etc/system file can exist for this tuning parameter. This number is the maximum value of System V semaphore operations per semop call. The default value for this option is too low for highly concurrent systems.
• How to view or set: Set this parameter through the /etc/system entry: semsys:seminfo_semopm = 200
• Default value: None
• Recommended value: 200 (100 is appropriate for most systems, but 200 might be needed in some cases.)

• Description: Change the following parameter when a high rate of incoming connection requests result in connection failures:

  ndd -get /dev/tcp tcp_conn_req_max_q 
  ndd -set /dev/tcp tcp_conn_req_max_q 8000

• Default value: For Solaris 8, the default value is 128.
• Default value: For Solaris 9 and Solaris 10, the default value is 128.
• Recommended value: 8000

Using large pages can reduce the CPU overhead of managing a large JVM heap.

With Solaris 9 and Solaris 10, large page support is provided by default. No operating system or JVM parameters are necessary to make use of large pages for the JVM heap.