Incident Library
  • Root cause
  • Component
  • Symptom
  • Contributing factor
  • Case

Cases2 cases

1 to 2 of 2

  1. Symptoms

    From about 21:00 UTC on March 4, 2026, customers using Linodes backed by NVIDIA RTX 4000 Ada GPUs saw the GPUs lock up. At first the problem seemed limited to worker nodes of the Linode Kubernetes Engine (LKE); later Linode confirmed that every Linode with this hardware was affected, while Standard Compute and other GPU instances were not.

    Trigger

    Deployment of a repaired legacy GPU monitoring script, fixed during a routine improvement effort to restore a missing metric on internal observability dashboards.

    Root cause
    Component
    Contributing factor
    Detection

    Customers saw the lockups from about 21:00 UTC; the first status post went up at 02:07 UTC on March 5, about 5 hours after the lockups began.

    Remediation
    • Disabled the monitoring script across the GPU fleet
    • Rebooted the affected nodes
    Action items
    • Take improvement and prevention measures to stop a recurrence; the postmortem does not list them
    Lessons

    A monitoring script can take down the hardware it watches. A fix meant only to restore a missing metric brought back a firmware query written for an earlier GPU generation, and on the RTX 4000 Ada architecture that query against an active GPU triggers a lockup. The script ran across the GPU fleet, so every Linode with this GPU was affected in several regions, and the investigation first suspected a regression in the host hypervisor or the GPU firmware.

  2. Symptoms

    Every service in the homelab Kubernetes cluster stopped answering: the V-Rising server, Grafana, Jellyfin and Linkding were all unreachable, and the Kubernetes API was down, so the cluster could not be managed at all. The outage was found by hand, about 3 hours after it began, when someone tried to use the services.

    Trigger

    A power outage forced the Kubernetes master node to reboot.

    Root cause
    Component
    Contributing factor
    Detection

    Manually, when someone tried to access the services; there were no automated alerts.

    Remediation
    • Connected a monitor to the master node and read the boot logs, which showed the kernel panic
    • Booted the previous kernel version, which brought the system back
    • Removed the broken Nvidia packages with sudo apt-get remove --purge '^nvidia-.*' and ran sudo dpkg --configure -a
    • Found remaining broken packages with dpkg -l | grep -v ^ii and removed them by hand
    • Ran sudo apt-get install -f and reinstalled linux-headers-$(uname -r)
    • Rebooted and confirmed the kernel panic was gone
    Action items
    • Make sure GPU driver installations fully succeed, or revert immediately when they fail
    • Move the cluster to a high-availability control plane
    • Expose the Kubernetes API through a load balancer in the HA setup
    • Set up a ticketing system to record incidents and their resolution
    • Write predefined troubleshooting workflows to shorten response time
    • Add infrastructure monitoring such as Prometheus and Grafana
    • Add blackbox HTTP and TCP checks from outside the cluster for critical services
    Lessons

    A driver installation that fails half-way can leave kernel packages broken without any visible effect until the next reboot, which may come weeks later and at the worst time. A failed DKMS build should be fixed or reverted at once. With a single master node and no monitoring from outside the cluster, one unbootable machine meant a total outage that nobody was told about; the fix itself was simple once the boot logs were seen.

Check your cluster for this

These 2 cases involve GPU driver and Kubernetes API server. kubegap audits a Kubernetes cluster for gaps like these, read-only, from Claude Code or Codex; its checks cite public reports like the ones in this library.

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