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Atlas Sharded Clusters

A sharded cluster is the set of nodes comprising a sharded MongoDB deployment. To view the metrics for a specific Atlas cluster in a project, click the Metrics button for that cluster. Alternatively, click on the name of the cluster to open the cluster overview, then click the Metrics tab.

The Metrics tab for sharded clusters provides a side-by-side comparision of shards in one view. The Display drop-down contains many available metrics.

Monitor cluster metrics to identify performance issues and determine whether your current cluster tier meets your requirements.

The Metrics view has three distinct sections:

Note
Monitoring Data Storage Granularity

Atlas stores metrics data at increasing granularity levels. For more information, see Monitoring Data Storage Granularity.

Atlas provides the following controls for the Metric view:

Control
Function
Granularity

Modifies the granularity of metrics displayed for each chart. Select a granularity between 1 minute and 1 day (24 hours). Select Auto to automatically adjust the granularity based on the selected Zoom or Current Display date controls.

Auto granularity selects the highest fidelity granularity available within the selected time range and sharded cluster metric rendering limits.

Note
Sharded Cluster Metric Rendering Limits

In the Sharded Cluster metrics view, Atlas renders a maximum of:

  • 100,000 total data points and
  • 3,000 data points for a single series.

As a result, when rendering metrics for large deployments over a long period of time, Atlas may display metrics at a lower granularity than expected. To learn more about the granularity at which Atlas stores metric data, see Monitoring Data Storage Granularity.

Zoom
Modifies the date range of metrics displayed for each chart. Select a zoom range between 1 hour and 5 years. Adjusting the Zoom automatically adjusts the Current Display date range.
Current Display
Modifies the start and end date-time range of metrics displayed for each chart. Modifying the start and end date sets the value of Zoom to custom and overrides the previously selected zoom level.
Display
Selects which metric to chart. You can display no more than one chart at a time.
Display Data

Directs Atlas to display data based on the selected option

  • Individually - displays the selected metrics for each shard as an individual line.
  • Sum - displays the sum of the selected metrics across all shards in the cluster.
  • Averaged - displays the average of the selected metrics across all shards in the cluster.
View

Selects which sharded cluster components to display

  • SHARDS - displays metrics for each shard in the sharded cluster.
  • MONGOS - displays metrics for each mongos in the sharded cluster.
  • CONFIGS - displays metrics for the config server in the sharded cluster config server replica set.

When viewing charts, you can do the following:

Task
Action
Zoom in on a period of time.

Click and drag the mouse pointer over a portion of the chart. To reset to the originally selected range (zoom out), double-click the chart.

Note

When you zoom in on one period of time, the Current Display date range in the chart control section automatically updates to reflect the selected period.

View statistics at a particular time.
Hover the mouse pointer over a point on the chart.

Atlas displays each data source that contributes to the metric chart in a table below the chart. The table consists of the following:

Column
Description
Shard Name

When View is set to SHARDS, displays the name of each shard in the sharded cluster.

When View is set to MONGOS or CONFIGS, displays the name of each mongos or config server mongod process in the cluster.

Click on a listed component to open the Metrics view for that component.

Alerts
Indicates if there are any open alerts for the listed shard or process. Click on the alert icon to open the Alerts view for that shard or process. For more information on responding to open alerts, see Resolve Alerts.
Data Size

Only visible if View is set to SHARDS.

Indicates the logical size of all documents and indexes on the shard.

Show

Only visible if View is set to SHARDS

Indicates which replica set members to show on the selected chart. Select Primaries, Secondaries or All.

Read, Write, and Queued
Metric data related to the displayed chart. Hover over the corresponding column for a pop up with detailed information on the metrics shown.
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