IBM Support

Configuration guidelines for the CCRC WAN server

Question & Answer


How do you configure the CCRC WAN server to ensure optimal performance and high scalability for ClearCase Remote Client (CCRC) users in ClearCase Version 8.0 and later?


NOTE: These guidelines are derived from benchmark testing on servers with the minimum recommended hardware configuration. The testing entailed various commonly used ClearCase operations with an average transaction rate of 15 operations per hour per user. Start with the settings listed in this document and then adjust them based on your expected peak load.

Required System Resources

All platforms
    • 8 GB of memory. If the CCRC WAN server is to host more than a single WAS profile (for example, ClearCase, ClearQuest, Requisite Pro), additional resources may be needed.
    • Quad-core server CPUs provide a strong processor base.
    • Services associated with the CCRC WAN server profile e.g. IBM WebSphere Application Server V7.0 - ccrcprofile must be set to allow the service to interact with the desktop system:
      Click Administrative Tools->Services
      Right-click IBM WebSphere Application Server V7.0 - ccrcprofile
      Click Log On
      Select Allow service to interact with desktop
      Set Windows registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\SessionViewSize to 96 or 192 based on expected peak load.

      Start with 96 and increase to 192 if out-of-memory errors are seen in CCRC WAN server profile's SystemOut.log e.g. \Program Files\IBM\RationalSDLC\Common\ccrcprofile\logs\server1\SystemOut.log during peak load.

All UNIX/Linux
    • The minimum requirement for swap space is twice the size of memory.
    • Increase the maximum number of open file descriptors to handle the user load. Refer to operating system documentation for instructions on how to set this parameter. CAUTION: Setting this value too high increases size of the ClearCase back end (CCBE) and view server processes. Start with 16K file handles and then adjust as needed.

Solaris 10

    Disable the Nagle algorithm using the following command:

    ndd -set /dev/tcp tcp_naglim_def 1


    • Use an AIX Power 5, 6 or 7 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 fixinfo112964: Fix pack information for: PORTMAPPER HANGS
    • 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 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.

    no -o clean_partial_conns=1

    Specifies whether synchronize-the-sequence-number (SYN) attacks are avoided. Enable this option 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 allows the ACK packet to piggyback on a response and minimizes the system overhead.

    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 CCRC WAN server are hosted on a Windows system, enable this parameter for optimal performance.


    • Increase the following tunable kernel parameter:

    • Disable the Nagle algorithm:

    ndd -set /dev/tcp tcp_naglim_def 1


    • If PAM authentication is in use
      cd /etc/pam.d
      cp login clearcase
      Edit file clearcase and comment out the line that contains the string securetty (usually the first line).
    • Increase max # files, edit /etc/security/limits.conf and set lines as follows:

    * soft nofile 16383
    * hard nofile 16383

CCRC WAN server Parameters

CCRC WAN server configuration parameters are defined in

<CC_HOME>/config/ccrc/server.conf e.g. c:\Program Files\IBM\RationalSDLC\Clearcase\config\ccrc\server.conf

For reference, use


  • ccrcLoginSessionTimeout
    Description : Lifetime of an idle CCRC session. Session is terminated after timeout.

    Value : Time interval in seconds

    Default : 1800 seconds

    Note : Timeout may be reduced for increased scalability. Recommended minimum is 900 seconds.
  • ccrcPrimaryGroup
    Description : Primary Group to be effective for CCRC users.

    Value : An operating system group that is valid on the server.

    Default : NONE

    Note : The effective primary group for all CCRC users using this server. This does not affect non-CCRC users.

  • ccrcTempDir
    Description : Pathname to temporary directory used by the server.

    Value : Pathname to a valid local directory with write access granted to all CCRC users.

    Default : (Windows)C:\temp\ccrctemp (modifiable during install)
    (UNIX/Linux)/var/tmp/ccrctemp (modifiable during install)

    Note : This pathname can be also be set during installation. CCRC login fails if a user does not have write access to this directory.

  • ccrcUploadLimit
    Description : Maximum size of file that may be uploaded to the server.

    Value : Size in Kbytes.

    Default : 15

    Note : Set only to limit the size of files that can be uploaded to the server.

  • ccrcUseViewHostPathForGlobalPath
    Description : Use global pathname to access view storage.

    Value : true or false

    Default : false

    Note : This must be specified when view storage is not local to the server. It must be true for load balancing.

  • ccrcViewStorage
    Description : Path name to view storage.

    Value : Valid local pathname if ccrcUseViewHostPathForGlobalPath=false. Valid global if ccrcUseViewHostPathForGlobalPath=true.

    Default : On Windows,
        • CC_HOME\var\ccweb if CC_HOME path does not contain embedded spaces
        • CC_HOME drive root:\ccweb if CC_HOME path contains embedded spaces
    On Unix/Linux, /var/adm/rational/clearcase/ccweb

    Note : This path should be outside the ClearCase installation location for ease of upgrade. Use this in conjunction with ccrcUseViewHostPathForGlobalPath.
  • ccrcVobLineTerminator
    Description : VOB line terminator for this server.

    Value : LF or CR-LF

    Default : None

    Note : Set appropriately for a configuration of mixed platform types.
  • ccrcClearQuestDatabaseMapFile
    Description : Pathname of the ClearCase/ClearQuest integration configuration file.

    Value : Valid pathname of local file.

    Default : None

    Note : Applicable only to CCRC users.
  • ccrcDownloadCompressionThreshold
    Description : Minimum file size to be compress prior to download to client.

    Value : Kbytes

    Default : 15

    Note : Setting this value too low can adversely affect performance.

  • ccrcSupportsParallelLoad
    Description : Flag to toggle enablement of parallel web view loads.

    Value : true or false

    Default : true

    Note : Refer to technote 1515393: About CCRC WAN Server parallel view loading for details. Modify this parameter in conjunction with ccrcMaxRequestsPerSession, ccrcMaxRequestsOverall and ccrcMaxSessionsOverall. See Note below.

  • ccrcMaxRequestsPerSession
    Description : Maximum number of simultaneously active requests per session.

    Value : > 0

    Default : 10

    Note : Modify this parameter in conjunction with ccrcSupportsParallelLoad, ccrcMaxRequestsOverall , ccrcMaxSessionsOverall and ccrcSupportsParallelLoad. See Note below.

  • ccrcMaxRequestsOverall
    Description : System-wide limit of simultaneously active requests.

    Value : > 0

    Default : 300

    Note : Modify this parameter in conjunction with ccrcSupportsParallelLoad, ccrcMaxRequestsPerSession and ccrcMaxSessionsOverall. See Note below.

  • ccrcMaxSessionsOverall
    Description : System-wide limit on number of simultaneously active sessions.

    Value : > 0

    Default : 200

    Note : Modify this parameter in conjunction with ccrcSupportsParallelLoad, ccrcMaxRequestsPerSession and ccrcMaxRequestsOverall. See Note below.

  • ccrcMaxRequestsPerSession * ccrcMaxSessionsOverall = the maximum number of active CCBE (ClearCase Back End) processes expected when ccrcMaxSessionsOverall number of CCRC sessions are active with peak activity. Each instance of CCBE processes only one request at a time.
  • ccrcMaxRequestsOverall should NOT be set to (ccrcMaxRequestsPerSession * ccrcRequestsPerSession). ccrcMaxRequestOverall should be set to the maximum number of CCBE processes (in addition to other processes on the server machines e.g. view servers, etc) that are sustainable on the system (based on system resources).
  • Refer to technote 1515393 for configuration guidelines for Parallel Web View load.
  • Set WAS thread pool max limits to be >= maxRequestsOverall.

WAS Configuration parameters for the CCRC WAN server Profile
Use the WAS console (http://server:port/ibm/console) to make changes. The port for the console is listed in <profile-home>/logs/server1/AboutThisProfile.txt, where <profile-home> is the CCRC profile's home directory. See "Commonly Used Commands" below.

The default values are applied to the default CCRC WAN server Profile, ccrcprofile, if a new profile is created during install.

If the CCRC WAN server is deployed in an existing profile, the defaults must be applied after careful consideration if the profile is shared with other applications.

To apply the default values to the profile hosting the CCRC WAN server :
    • In a command window, change directory to :
        On Windows, <ccase-home-dir>\var\web, where <ccase-home-dir> is the location of where ClearCase is installed e.g. C:|Program Files\IBM\RationalSDLC\Clearcase
        On UNIX/Linux, /opt/rational/clearcase/web

    • Run the following command :

      On Windows, <profile-home>\bin\wsadmin.bat -c "source ccrcAdminUtils.jacl" -c "setCCRCRecommendedDefaults"

      On UNIX/Linux, profile-home/bin/ -c "source ccrcAdminUtils.jacl" -c "setCCRCRecommendedDefaults"

      where <profile-home> is the CCRC profile's home directory. See "Commonly Used Commands" below.

Servers->Server Types>WebSphere Application Server>server1>Web container>Custom property

Servers>Server Types-WebSphere Application Server>server1>Web container transport chains>WSInboundDefault>Http inbound channel
    Write timeout=300 seconds
    Persistent timeout=120 seconds

Servers>Server Types>WebSphere Application Server>server1>Process definition>Java Virtual Machine
    Initial heap size=1024 MB
    Maximum heap size=1024MB

Servers>Server Types>WebSphere Application Server>server1>Thread Pools
    Web Container=300

Environment>WebSphere Variables>

Troubleshooting>Logging and Tracing>server1>Diagnostic trace service
    Maximum File Size=20MB
    Maximum number of Historical files=20

Commonly Used Commands

This section contains commonly used command referred to in this document.

Locating the WAS profile home directory (profile-home)
    In a command window, enter the command :

    On Windows, <was-home>\bin\manageprofiles.bat -getPath -profileName <profile name>

    On UNIX/Linux, <was-home>\bin\ -getPath -profileName <profile name>

    where <was-home> is the WebSphere installation location.

Listing WAS profiles on the system
    In a command window, enter the command :

    On Windows, <was-home>\bin\manageprofiles.bat -listProfiles

    On UNIX/Linux, <was-home>\bin\ -listProfiles

    where <was-home> is the WebSphere installation location.

[{"Product":{"code":"SSSH27","label":"Rational ClearCase"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Component":"CCRC WAN Server","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF015","label":"IRIX"},{"code":"PF016","label":"Linux"},{"code":"PF022","label":"OS X"},{"code":"PF027","label":"Solaris"},{"code":"PF033","label":"Windows"}],"Version":"8.0;;;;;;;;;;8.0.1;;;;;;;;;;;9.0","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
01 August 2018