IBM Support

Change Management Server configuration guidelines for ClearCase Remote Client in ClearCase version 7.1

Technote (FAQ)


How do you configure the Change Management Server (CM Server) to ensure optimal performance for ClearCase Remote Client (CCRC) users in ClearCase version 7.1 and higher?


System Resources

All Platforms

  • CM Server host must have a minimum of 8 GB of memory.

    • Swap space on UNIX machines must be twice the size of memory at a minimum.

    Solaris SPARC

    Solaris 9
    Add the following to lines to /etc/system:

    set shmsys:shminfo_shmmax = 4294967295
    set shmsys:shminfo_shmseg = 1024
    set shmsys:shminfo_shmmni = 1024
    set semsys:seminfo_semaem = 16384
    set semsys:seminfo_semmni = 1024
    set semsys:seminfo_semmap = 1026
    set semsys:seminfo_semmns = 16384
    set semsys:seminfo_semmsl = 100
    set semsys:seminfo_semopm = 100
    set semsys:seminfo_semmnu = 2048
    set semsys:seminfo_semume = 256
    set msgsys:msginfo_msgmap = 1026
    set msgsys:msginfo_msgmax = 65535
    set rlim_fd_cur=65535

    Solaris 10
    Run the following commands:

    projmod -s -K 'project.max-shm-memory=(privileged,4gb,deny)' user.root
    projmod -s -K 'project.max-shm-ids=(privileged,1024,deny)' user.root
    projmod -s -K 'project.max-sem-ids=(privileged,1024,deny)' user.root
    projmod -s -K 'process.max-sem-nsems=(privileged,512,deny)' user.root
    projmod -s -K 'process.max-sem-ops=(privileged,512,deny)' user.root
    projmod -s -K 'process.max-file-descriptor=(privileged,65535,deny)' user.root

    These settings persist in /etc/project.

    Solaris 10
    Disable the Nagle algorithm by using the following command:

    ndd -set /dev/tcp tcp_naglim_def 1
        • Use an AIX Power 5 or Power 6 host system.
        • You must install the fix for APAR IZ55804 (AIX 5.3) or IZ52038 (AIX 6.1) to correct a problem that causes the portmapper daemon to hang. The fix is included in the 5300-11 technology level. To obtain the fix for AIX 6.1 refer to
        • Set the following operating system parameters:
          no -o tcp_nagle_limit=0

            Most TCP implementations use the Nagle algorithm, where a TCP connection can have only one outstanding small segment that has not been acknowledged. This issue causes TCP to delay sending further packets until it receives an acknowledgement or until it can bundle more data and send a full-size segment.

            You must disable the Nagle algorithm when using the ClearQuest Web application.

          no -o clean_partial_conns=1

            Specifies whether synchronize-the-sequence-number (SYN) attacks are avoided.

            Enable this option for the ClearQuest Web application to protect against network attacks.

          no -o tcp_nodelayack=1
            Enabling this parameter causes TCP to send immediate acknowledgement (ACK) packets to the sender. When the parameter tcp_nodelayack is off, TCP delays sending ACK packets by up to 200 ms. This issue allows the ACK packet to piggyback on a response and minimizes the system over-head.

            For optimal performance, enable this parameter.
            no -o rfc1323=1

            Enables window scaling and time stamps as specified by RFC 1323 (TCP Extensions for High Performance). Window scaling allows the TCP window sizes ( tcp_recvspace and tcp_sendspace) to be larger than 64 KB (65,536) and is typically used for large maximum transmission unit (MTU) networks.

            If your ClearCase VOBs or ClearQuest databases are hosted on a Windows system, enable this parameter for optimal performance.
          ulimit -d -n

          The default limits are not sufficient to support peak CCRC load.

          To make AIX tunable changes permanent or present after reboot, the -p flag should be used.
        • Increase the following tunable kernel parameter:


        • Disable the Nagle algorithm:
            ndd -set /dev/tcp tcp_naglim_def 1

        • cd /etc/pam.d
        • cp login clearcase
        • Edit file clearcase and comment out the line that contains the string securety (usually the first line).

    • For CCRC only
      1. Services associated with the CM Server profile IBM WebSphere Application Server V6.1 - cmprofile must be set to allow the service to interact with the desktop system:
        1. Click Administrative Tools > Services.
        2. Right-click IBM WebSphere Application Server V6.1 - cmprofile.
        3. Click Log On.
        4. Select Allow service to interact with desktop.
      2. Increase the desktop heap size. See the following technote for details:
      3. Set SessionViewSize to 96 or 192 based on expected peak load. Start with 96 and increase to 192 if out-of-memory errors occur in \Program Files\IBM\RationalSDLC\Common\CM\profiles\cmprofile\logs\server1\SystemOut.log during peak load.

    CM Server Parameters
    The CM Server may be tuned for optimal performance for CCRC users based on expected peak load (concurrent CCRC users). The following list of parameters can be adjusted to achieve the desired performance level. See the CM Server information in the Administering ClearCase information center MBean topic for instructions on how to modify these MBeans.
    • maxServersPerCredential - Default value is 5. Must be equal to or greater than 2.

      Purpose: Limits the number of ClearCase RPC processes that can be active for one set of user credentials (domain, username, ClearCase primary group, ClearCase groups).

      Configuration: The default value is 5, which works well on CM Servers that host large numbers of CCRC users. If the server is expected to serve only a few users at peak load, this value can be increased to give each user more system resources.

      Notes: Setting this value too high can cause fewer users to access ClearCase simultaneously. Setting this value too low can cause ClearCase operations to take longer for each ClearCase user who is logged on.
    • serverThresholdCount – Default value is 200. Must be equal to or greater than 0.
      Purpose: One of the parameters governing the life of each ClearCase RPC process. Lifecycle management becomes effective after the total number of active ClearCase RPC processes is larger than this count.

      Configuration: Constrained to a value that is less than or equal to maxServerCount. If you need to increase this value, increase the maxServerCount value first, if needed. This value should be set to the average number of CCRC users that will access the CM server.

      Notes: Reducing the value makes the lifecycle management process run more frequently. Values too low will cause the system to be affected by the over-head of stopping and starting processes.
    • maxServerCount - Default value is 300. Must be equal to or greater than 1.

      Description: The maximum number of ClearCase RPC processes that can be active at a given time.

      Configuration:: Constrained to a value that is greater than or equal to serverThresholdCount. If you need to decrease this value, decrease the serverThresholdCount value first, if needed. This value should be set to 1.5 times the average number of CCRC users that will access the CM server.

      Notes: The value of this MBean dictates the resource usage on the host server. When choosing a value, you must consider the resource limits of the server.

    WebSphere Application Server Parameters
    Use the WebSphere Application Server (WAS) admin console to set the following parameters as needed. Access the WAS admin console using http://localhost:12060/ibm/console
      • J2C Connection pool - Default value is 400.

        Description: The maximum number of connections to ccrpc backend processes.

        Configuration:: Increase the J2C Connection pool value "Maximum Connections" if you increase the CcServerFactoryMBean value for "Maximum RPC server processes" (maxServerCount).

        The Maximum Connections value is located at: Applications > Enterprise Applications > TeamEAR > Manage Modules > OncrpcConnector > Resource Adapter > J2C connection factories > CcRpc >
        Connection pool properties

      • Thread Pools - Default maximum for both Default and WebContainer pools is 200.

        Description: Maximum size of thread pools used by CM Server. Enabling thread allocation beyond the maximum size avoids the need to customize these values based on server load.

        Configuration: If there are more than 200 CCRC users who will access the CM Server, modify the default thread pool settings by navigating to Servers > Application servers > server1 > Thread Pools > Default and ensure that Allow thread allocation beyond maximum thread size is selected in the "Additional Properties" section.

        Also modify the Web Container thread pool settings by navigating to Servers > Application servers > server1 > Thread Pools > WebContainer and ensure that Allow thread allocation beyond maximum thread size is selected.

    Document information

    More support for: Rational ClearCase
    ClearCase Remote Client

    Software version: 7.1, 7.1.1,,,,,,,,,, 7.1.2,,,,,,,,

    Operating system(s): AIX, HP-UX, Linux, Solaris, Windows

    Reference #: 1327082

    Modified date: 15 October 2012

    Translate this page: