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Syslog message: XMCHIP.*MALLOC: SChunk allocation memory parity error



Article ID: KB31607 KB Last Updated: 07 Oct 2021Version: 3.0

The "SChunk allocation memory parity error" message reports a transient hardware error.

This is a Troubleshooting Article for a PFE ASIC Syslog Event.
To view other documented syslog events related to XMCHIP, XLCHIP, MQCHIP, LUCHIP, EACHIP, and PECHIP, see KB31893 - Index of Articles for Troubleshooting PFE ASIC Syslog Events.


When a "SChunk allocation memory parity error" event occurs, a message similar to the following is reported:
Feb 27 14:09:14 router0 fpc10 XMCHIP(1): MALLOC: SChunk allocation memory parity error - Address 0x77


  1. Single occurrence of syslog, if not seen with other events, indicates a one time hardware error. Multiple continuous occurrences indicate persistent underlying issues.
  2. No permanent impact of packet forwarding.
  3. Alarm will be raised.
  4. For the each error entry, a few data traffic packet drops could be seen, but the losses aren’t persistent and traffic should resume to 100%, as before.



The cause is due to a hardware parity error detected in chip memory.  If there is a service impact then other events will be reported.



Perform these steps to determine the cause and resolve the problem (if any).  Continue through each step until the problem is resolved.

  1. Collect the show command output.

    Capture the output to a file (in case you have to open a technical support case). To do this, configure each SSH client/terminal emulator to log your session.

    show log messages
    show log chassisd
    start shell network pfe <fpc#>
    show nvram
    show syslog messages

  2. Analyze the show command output.

    In the 'show log messages', review the events that occurred at or just before the appearance of the "SChunk allocation memory parity error" message. Frequently these events help identify the cause.

    • No RMA required.
    • With the single occurrence, the alarm can be cleared using command:
      clear chassis fpc errors fpc-slot <x> all
      Note: This command is available in Junos OS 16.1R4-S2, 16.1R5, 16.2R2, 17.1R2, and 17.2R1 or higher.
    • The multiple continuous occurrences of errors require FPC restart during maintenance window to clear the alarms.
    • Contact your technical support representative if the issue is seen after a FPC restart.

This article is indexed in KB31893 - Primary Index of Articles for Troubleshooting PFE ASIC Syslog Events; tag XMCHIPTSG

Tip: When looking at an event in the logs, it is important to focus on the first error message in a collection of syslog messages. The first error message is usually the cause of all the follow-on error messages. The follow-on collateral damage error messages can be ignored.


Modification History:
2019-10-14: Article reviewed for accuracy; no changes required.
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