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Frequently Asked Questions

FAQ: Storage

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  • What happens when I reach my Atlas storage limit?
  • Without using Provisioned IOPS on MongoDB Atlas on AWS, what kind of IOPS should I expect?
  • Can I configure a cluster with more storage than the standard limit for the cluster tier?

What happens when I reach my Atlas storage limit?

The result of reaching your Atlas storage limit depends on the Atlas cluster you are using.

  • For M0 and Flex clusters, the maximum storage is a hard limit and cannot be exceeded. You can add additional storage by upgrading to a dedicated cluster (M10+). For details on how Atlas calculates storage limits for Flex clusters, see this section of the FAQ.

  • By default, M10+ clusters auto-expand storage based on disk usage thresholds. To modify this setting to a fixed storage limit, refer to the Modify a Cluster page.

If you attempt to write to a Flex cluster that does not have space for the desired write operation, Atlas displays an error message similar to the following:

WriteResult({
  "writeError": {
    "code": 8000,
    "errmsg": "you are over your space quota, using 513 MB of 512 MB"
  }
})

Tip

See also:

To learn about the differences between Flex clusters and dedicated clusters, see Atlas Flex Limits.

Tip

You can configure alerts which trigger once your allocated storage reaches a specified threshold. Atlas calculates allocated storage using metrics returned by the dbStats command.

Atlas retrieves database metrics every 20 minutes by default but adjusts frequency when necessary to reduce the impact on database performance.

To learn more about storage alerts, see DB Storage alert conditions.

How does Atlas calculate storage limits for Flex Clusters?

Atlas calculates the storage limit for Flex clusters based on data usage, as opposed to the storageSize metric used by non-Flex clusters (which includes compression). Atlas determines data usage by summing a cluster's dataSize and indexSize. You can issue the db.stats() method to view the values of these fields.

Without using Provisioned IOPS on MongoDB Atlas on AWS, what kind of IOPS should I expect?

Atlas provides an estimate of how many 16K IOPS you can expect, calculated as the lesser of 3 IOPS per provisioned GB, or the cluster node's maximum IOPS capacity.

Can I configure a cluster with more storage than the standard limit for the cluster tier?

For clusters that meet specific criteria, yes. To learn which clusters support extended storage and how to enable this for your projects, see Manage Project Settings.

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