IL-0375 MongoDB · 2024-06-03database
MongoDB Atlas cluster changes and alerts lagged for hours after a control plane metadata migration congested a database
The Atlas control plane relies on an internal workflow management system whose metadata MongoDB planned to migrate to a target database cluster. When traffic was redirected to the target, the target cluster became congested on resources, which had not happened in pre-production testing, and cluster configuration changes and alert processing ran with delays of a few minutes to several hours, while lower-granularity cluster metrics and parts of the Atlas UI were unavailable or impaired. Rolling back needed complex reconciliation of the data in the source and target databases, which delayed recovery. Recovery procedures were complete at 00:09 UTC on 4 June, the degradation ended at 1:21 UTC, and the incident was marked resolved at 02:11 UTC. MongoDB said customers did not need to take any action.
- Severity
- –
- Scope
- Atlas cluster configuration changes from the API and automated triggers, alert processing and integrations, lower-granularity cluster metrics, Data Explorer, Real-Time Performance Panel and daily cost tabulation
- Users affected
- MongoDB Atlas customers
- Region
- All commercial regions
- Time to detect
- –
- Time to resolve
- 6h 57m
Symptoms
From 18:24 UTC on 3 June 2024, MongoDB Atlas cluster configuration changes in all commercial regions ran with delays of a few minutes to several hours. The delays hit changes requested through the API and changes from automated triggers such as auto-scaling and node replacement.
Alert processing was delayed in the same way, for the Atlas built-in alerts and for integrations such as Datadog and PagerDuty. Lower granularities of cluster metrics were unavailable until up to 1:56 UTC on 4 June, the Data Explorer and Real-Time Performance Panel interfaces were impaired for several hours, and part of the daily cost tabulation for compute, storage and data transfer for 3 June was pushed to 6 or 7 June.
The status page first reported delays in all cluster updates across all cloud providers at 18:45 UTC. By 21:31 UTC the root cause had been identified and recovery had begun. At 23:07 UTC, cluster operations submitted between 18:45 and 21:55 UTC could still be delayed or hold up later changes, while operations submitted from then on were expected to run normally.
Root cause
Root cause Capacity exhaustion
- Trigger
- During planned internal maintenance, the metadata of an internal workflow management system that backs the Atlas control plane was migrated to a target database cluster, and traffic was redirected to that target.
Detection
–
Remediation
- Rolled back the metadata migration, reconciling data between the source and target databases
- Executed recovery procedures, completing them at 00:09 UTC on 4 June, and kept monitoring closely
Action items
- Design a new metadata migration strategy that can roll back within 15 minutes of detecting a problem
- Hold similar maintenance activities until the new procedure is implemented and tested
Lessons
–
Sources
- https://status.mongodb.com/incidents/ds8dq4vkp6f9 · official-status · archived copy
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