A common issue when using MMAPv1 (less frequent with WiredTiger), is free disk space. As with memory, we need to track disk space usage and be proactive rather than reactive with it. Keep monitoring disk space usage with proper alerts when it reaches 40, 60, or 80% of disk space, especially for datasets that grow quickly.

Disk space issues are often the ones that cause the most headaches to administrators, DevOps, and developers because of the time it takes to move data around.