Navigation

Disk I/O % Utilization

Description

Disk I/O % Utilization alerts indicate that the percentage of disk IOPS utilized reaches a specified threshold. This threshold is specified when the alert is created.

Note

The utilization measurements for the following alerts include requests from all processes, not just MongoDB processes.

Disk I/O % utilization on Data Partition occurs if the percentage of time during which requests are being issued to any partition that contains the MongoDB collection data meets or exceeds the threshold.

Disk I/O % utilization on Index Partition occurs if the percentage of time during which requests are being issued to any partition that contains the MongoDB index data meets or exceeds the threshold.

Disk I/O % utilization on Journal Partition occurs if the percentage of time during which requests are being issued to the partition that contains the MongoDB journal meets or exceeds the threshold.

Possible Observations

These are a few possible methods to observe high Disk I/O % Utilization:

  • The disk IOPS use from the Disk IOPS graph in the cluster metrics is higher than the provisioned IOPS from the Atlas cluster configuration page.
  • There is a high IOWait curve in the Normalized System CPU metric. IOWait measures the percentage of time the CPU is idle and waiting for an I/O operation to complete. The Normalized System CPU chart is located under the Hardware Metrics section of the Metrics tab.

Common Triggers

These are a few common events which may lead to high Disk I/O % Utilization and trigger these alerts:

  • Unoptimized queries can cause extra disk IOPS usage.
  • There may be a one-time event which causes a spike in disk IOPS and exceeds the IOPS threshold, such as an index build.

Possible Solutions

These are a few possible actions to consider to help resolve Disk I/O % Utilization alerts: