How to Generate Core Dump on an Unresponsive NetScaler Appliance

How to Generate Core Dump on an Unresponsive NetScaler Appliance

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Article ID: CTX133923

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Description

This article describes how to generate a core dump on an unresponsive NetScaler appliance.

Background

Unresponsiveness is a situation where the process runs in a never-ending loop. One sign of unresponsiveness is when the device appears to power up but does not respond to any inputs. There can be cases where NetScaler continuous to handle the traffic while being unreachable through GUI/SSH/Console.

In case the NetScaler is unresponsive, you may not see any core dumps. A reboot will almost certainly restore access to the unit, but it should not be the first line of troubleshooting as this will result in important diagnostic information being lost. You should instead attempt to dump the core.

    Instructions

    NetScaler SDX

    You either use the Non-Maskable Interrupt Button on NetScaler or the following procedure to dump core on NetScaler SDX appliance.

    Connect to the XenServer console by using the serial cable or virtual console. Refer to CTX121442 - How to Configure Serial Console Access on XenServer and CTX127966 - How to Set Up Netconsole on XenServer for more information.

    To retrieve diagnostic information from a XenServer/dom0/NetScaler SDX appliance that is not responding, complete the following procedure:

    1. Press the Enter key a couple of times to verify if the dom0 console is responding.
    2. If the dom0 console is trying to log on, then run the ls command.
    3. If the expected output is displayed, then verify the network connectivity.
    4. If dom0 is only partially responsive, then send the normal Linux SysRq keys such as m for memory and t for task list.
      Note: To send a SysRq to dom0 press Ctrl+O followed by the key. You never actually press the SysRq key.
    5. Verify if XenServer is responding after you press Ctrl+A three times. If XenServer responds, then it should display a line that it is receiving input.
    6. Now press * to dump all XenServer diagnostics.
      Note: To exit this mode and to send serial input to dom0, press Ctrl+A three times again.
    7. If dom0 is not responding but XenServer is responding, then you can attempt to retrieve a crash dump from the XenServer by pressing C while input is directed to XenServer.

    Refer to CTX120540 - How to Generate a Crashdump from an Unresponsive XenServer for more information.

    NetScaler MPX/VPX

    Refer to CTX207598 - How to Generate NSPPE Core Dump on NetScaler for information on dumping the core on NetScaler MPX/VPX appliance when the console is available.

    Refer to CTX120660 - The Non-Maskable Interrupt Button on a NetScaler Appliance for information on dumping the core on NetScaler MPX appliance when NetScaler is completely unresponsive.

    Refer to CTX227052 - How to Generate Crash Dump on Unresponsive NetScaler VPX Hosted on XenServer for information on generating crash dump on unresponsive NetScaler VPX hosted on XenServer.

    Download Core File

    Refer to CTX133923 - How to Generate Core Dump on an Unresponsive NetScaler Appliance

    Refer to CTX207598 - How to Generate NSPPE Core Dump on NetScaler for High Memory issues

    Issue/Introduction

    This article describes how to generate a core dump on an unresponsive NetScaler appliance.

    Additional Information

    The crash dump might not work on NetScaler SDX appliance; success depends on the condition of the appliance.

    Disclaimer

    Caution! This article contains content that is experimental and is not an officially supported Citrix solution. Citrix cannot guarantee that problems resulting from this implementation can be solved or supported. It is provided to you as an option that has not been fully tested. Use this at your own risk.

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