Resolved incident

Fly.io Upstash Redis Service Distruption

Upstash · Critical · Started

Duration
3h 59m
Severity
Critical
Status
Postmortem

Summary

Critical · Postmortem

On May 12th and 13th at various times, a subset of Upstash Redis instances on [Fly.io](http://Fly.io) experienced intermittent hangs and elevated error rates. The Redis process would stall inside a logging syscall — alive but not making progress — which made the issue hard to spot from our usual telemetry. After investigating with Fly's team, we identified the root cause as a bad interaction between a recent guest kernel update on Fly's newer machines and an upstream Cloud Hypervisor bug \([cloud-hypervisor#7672](https://github.com/cloud-hypervisor/cloud-hypervisor/issues/7672)\) affecting log writes from inside the VM. We mitigated by disabling the affected logging paths, and Fly has since rolled out a hypervisor-side patch, fully resolving the issue. No data was lost. Sorry for the disruption.

View official incident ↗

Event timeline

How this incident unfolded, from the official status page.

  1. Investigating

    Upstash

    Some regions are experiencing connectivity issues due to an ongoing network problem. We are currently investigating

  2. Identified

    Upstash

    The issue has been identified and the fix is being implemented.

  3. Monitoring

    Upstash

    A fix has been implemented and we are monitoring the results.

  4. Resolved

    Upstash

    This incident has been resolved.

  5. Postmortem

    Upstash

    On May 12th and 13th at various times, a subset of Upstash Redis instances on [Fly.io](http://Fly.io) experienced intermittent hangs and elevated error rates. The Redis process would stall inside a logging syscall — alive but not making progress — which made the issue hard to spot from our usual telemetry. After investigating with Fly's team, we identified the root cause as a bad interaction between a recent guest kernel update on Fly's newer machines and an upstream Cloud Hypervisor bug \([cloud-hypervisor#7672](https://github.com/cloud-hypervisor/cloud-hypervisor/issues/7672)\) affecting log writes from inside the VM. We mitigated by disabling the affected logging paths, and Fly has since rolled out a hypervisor-side patch, fully resolving the issue. No data was lost. Sorry for the disruption.