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StarQuest Technical Documents

SQDR & SQDR Plus: TCP KeepAlive Settings

Last Update: 12 November 2021
Product: SQDR Plus
Version: 4.50 and later
Article ID: SQV00PL061

Abstract

In order for SQDR to react quickly to loss of connectivity to a source or destination system, or between tier 2 and 3 in a split-tier environment, we recommend examining and adjusting the TCP KeepAlive parameters. These recommendations apply to both Tier 2 and Tier 3 systems in a split-tier environment.

Solution

Windows recommendations

  1. Use regedit and open the key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
  2. Examine the following values, noting the original value(s). If there are registries that don't exist, these will be created later by running the keepAliveParams.ps1 PowerShell script
    • KeepAliveInterval: REG_DWORD = Interval between KeepAlive packets when one is dropped.
    • KeepAliveTime: REG_DWORD = How often TCP attempts to verify the connection.
    • TcpMaxDataRetransmissions: REG_DWORD = Number of retries TCP does for a packet before giving up.

  3. Download the keepAliveParams.ps1 onto the Windows machine
  4. Open a PowerShell Window as an administrator
  5. Relocate to the directory where the keepAliveParams.ps1 script resides.
  6. Run the script by running ".\keepAliveParams.ps1"
  7. Return to the regedit window and refresh the screen. Ensure that the registry entries have been created and their corresponding values set.
  8. Reboot the system for the changes to take effect.

Linux and Docker recommendations

  1. Login as the root user.
  2. Download the prep-host.sh onto /root on the Linux host.
    Note: If the installation is done through Docker, then the prep-host.sh script is included in the Docker image. After the container runs, copy the script by running "docker cp stelo-full:/opt/stelo/sqdrplus/Tools/prep-host.sh /root". This copies the script to the /root directory on the Linux host.
  3. Run chmod +x prep-host.sh to make the script executable.
  4. Run the prep-host.sh script by running ./prep-host.sh.
    Note: A reboot is not required as the changes to the system for adding keepalive parameters take effect immediately.

Note: Modifying the KeepAlive parameter settings may affect the operation of other applications on the computer.

For more information, see Configuring TCP KeepAlive Parameters.

DISCLAIMER

The information in technical documents comes without any warranty or applicability for a specific purpose. The author(s) or distributor(s) will not accept responsibility for any damage incurred directly or indirectly through use of the information contained in these documents. The instructions may need to be modified to be appropriate for the hardware and software that has been installed and configured within a particular organization.  The information in technical documents should be considered only as an example and may include information from various sources, including IBM, Microsoft, and other organizations.