MongoDB Chunk Migrations and Balancer Errors
Reads recent chunk move events and errors from the config database. Detects balancer problems and unnecessary migrations.
db.getSiblingDB("config").changelog.find(
{ what: /moveChunk/ },
{ time: 1, what: 1, ns: 1, details: 1 }
).sort({ time: -1 }).limit(20);Verify in a staging environment prior to running in production. This is a read-only diagnostic query; it does not acquire exclusive locks.
- This script is designed for read-only diagnostics; it does not alter schema or modify data directly.
- Prior to executing on production systems under high load, verify the target database version (Min. Version: 4.4).
- Exercise caution with mutating actions (e.g., terminating sessions or dropping indexes) referenced in the notes section.
Engineering Triad: Related Runbooks & Incident Response
Which production incidents and emergency drills execute this script as a diagnosis step?
Other MONGODB Diagnostic Scripts
View All (100)Find Long-Running Operations in MongoDB (currentOp)
Lists active operations running longer than 5 seconds with plan summary and lock-wait info. Helps pick the operation to kill during a slowdown.
MongoDB Collection and Index Sizes
Ranks collections by document count, data, storage and index size. Used for capacity planning and spotting bloated indexes.
Find Unused Indexes in MongoDB ($indexStats)
Lists never-used indexes per collection. Offers cleanup candidates to cut write cost and memory use.
MongoDB Replica Set Lag and Oplog Window
Shows member state, lag behind the primary and the oplog window. Monitors replication health and resync risk.