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CONTAP-727096: Unexpected Controller Reboots with "process on cpuXX hung (AssistThread)" in Large NFSv4.1/pNFS Environments

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ontap-9
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nas
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Issue

  • In certain environments running ONTAP with NFSv4.1, pNFS, and Session Trunking enabled, controllers experience unexpected reboots.
  • In large-scale deployments, repeated unexpected reboots result in service disruption and reduced access to hosted workloads.
  • The issue has been observed in environments with high levels of NFS activity and large numbers of connected clients.

Symptoms:
  • Unexpected controller reboots with string message:

process on cpuXX hung (AssistThread) for approximately 5000 milliseconds in SK process AssistThread on release 9.19.1P2
  • Repeated node failover/takeover events on HA pairs.
  • Service disruption for client workloads
  • Reduced accessibility to hosted data during affected events

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