24/7 replica set support with named senior engineers and no tier-1 triage
MongoDB
KubernetesTerraform
PrometheusThe recurring nightly resync was eliminated and the replica set now holds a replication window measured in days rather than hours. The customer's on-call team resolves most lag events from the runbook…
Overview
An analytics provider ran nightly ETL loads that generated far more oplog volume than steady-state traffic. Any secondary that fell behind during the load window rolled off the oplog and dropped into a full initial sync, which then competed with the next night's load. AceMQ took over replica set support with named senior engineers and direct escalation.
Challenge
The oplog was sized from the default percentage of disk at cluster creation and had never been revisited. Bulk updates that rewrote whole documents amplified oplog volume well beyond the size of the changed fields, and a single lagging secondary could trigger a resync cascade that left the set without a healthy read replica for most of a business day.
Environment
Managed MongoDB replica sets on AWS with nightly batch ingestion from an upstream clinical data warehouse.
Approach
AceMQ measured actual oplog churn during a full batch window rather than relying on averages, then sized the oplog to cover the worst observed window with headroom. In parallel, engineers reworked the batch writes to reduce oplog amplification and established a runbook so on-call staff could recover a lagging secondary without a full resync.
Solution
- 1Measured peak oplog generation rate across a complete batch window to size the oplog against worst case, not average
- 2Resized the oplog online and validated the resulting replication window under load
- 3Converted whole-document rewrites in the ETL to targeted field updates to cut oplog amplification
- 4Staggered batch load concurrency so secondaries could keep pace with primary write throughput
- 5Wrote a recovery runbook covering lagging secondaries, rollback files, and when a resync is genuinely required
- 6Set up replication lag and oplog window alerting tied to the 24/7 escalation path
Outcome
The recurring nightly resync was eliminated and the replica set now holds a replication window measured in days rather than hours. The customer's on-call team resolves most lag events from the runbook without escalating.
Technologies
MongoDBKubernetesTerraformPrometheusRelated Use Cases
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Need Expert MongoDB Support?
AceMQ's senior MongoDB engineers have handled this exact type of engagement before. Whether you need architectural guidance, hands-on remediation, or an ongoing managed partnership, we're ready to help.