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Configure Additional Options

You can configure the following mongod runtime options on M10+ paid tier clusters.

To view these settings, open the More Configuration Options under Additional Settings in the cluster form.

Image showing more cluster configuration options.

Modify the oplog size of the cluster.

For sharded cluster deployments, this modifies the oplog size of each shard in the cluster.

This option corresponds to modifying the replication.oplogSizeMB configuration file option for each mongod in the cluster.

Specify your desired Oplog Size in megabytes in the input box.

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If your change would reduce free disk space to below 25 percent, Atlas displays an error. Atlas doesn't change the oplog size until you choose a value above that threshold.

To check the oplog size:

  1. Connect to your cluster via the mongo shell.
  2. Authenticate as a user with the Atlas admin role.
  3. Run the rs.printReplicationInfo() method.

Atlas displays the current oplog size and time.

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Reducing the size of the oplog requires removing data from the oplog. Atlas cannot access or restore any oplog entries removed as a result of oplog reduction. Consider the ramifications of this data loss before reducing the oplog.

Do not reduce the size of the oplog as a means of increasing available disk space. Only the oplog collection (local.oplog.rs) can reclaim the space saved by reducing the oplog size. Other collections do not benefit from reducing oplog storage.

Enable or disable enforcement of the 1024-byte index key limit. Documents can only be updated or inserted if, for all indexed fields on the target collection, the corresponding index entries do not exceed 1024 bytes.

If disabled, mongod writes documents that breach the limit but does not index them. This option corresponds to modifying the failIndexKeyTooLong parameter via the setParameter command for each mongod in the cluster.

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Index Key Limit

failIndexKeyTooLong was deprecated in MongoDB version 4.2 and is removed in MongoDB 4.4 and later.

Enable or disable execution of operations that perform server-side execution of JavaScript.

  • If your cluster runs a MongoDB version less than 4.4, this option corresponds to modifying the security.javascriptEnabled configuration file option for each mongod in the cluster.
  • If your cluster runs MongoDB version 4.4 or greater, this option corresponds to modifying the security.javascriptEnabled configuration file option for each mongod and mongos in the cluster.
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In MongoDB version 4.4 and later, security.javascriptEnabled applies to mongos' as well.

Sets the minimum TLS version the cluster accepts for incoming connections. This option corresponds to configuring the net.ssl.disabledProtocols configuration file option for each mongod in the cluster.

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TLS 1.0 Deprecation

For users considering this option as a method for enabling the deprecated Transport Layer Security (TLS) 1.0 protocol version, please read What versions of TLS does Atlas support? before proceeding. Atlas deprecation of TLS 1.0 improves your security of data-in-transit and aligns with industry best practices. Enabling TLS 1.0 for any Atlas cluster carries security risks. Consider enabling TLS 1.0 only for as long as required to update your application stack to support TLS 1.1 or later.

Enable or disable the execution of queries that require a collection scan to return results. This option corresponds to modifying the notablescan parameter via the setParameter command for each mongod in the cluster.

Atlas dynamically modifies the Oplog Size for replica sets and sharded clusters. However, for the Minimum TLS Protocol Version and Allow Server-Side JavaScript settings, it performs a rolling restart of the shard members and the config server replica set. To learn more about how Atlas supports high availability during maintenance operations, see How does MongoDB Atlas deliver high availability?.

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