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MongoDB Ops Manager


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  • Logs Display MongodVersionException
  • Insufficient Oplog Size Error

The MongodVersionException can occur if the Backup Daemon's host cannot access the internet to download the version or versions of MongoDB required for the backed-up databases. Each database requires a version of MongoDB that matches the database's version. Specifically, for each instance you must run the latest stable release of that release series.

If the Daemon runs without access to the internet, see Configure Deployment to Have Limited Internet Access to install the appropriate binaries.

If you have set the mms.backup.minimumOplogWindowHours, Ops Manager checks to see if the cluster's oplogs can store a given number of hours of data. It bases on recent oplog usage patterns from the last 24 hours.

If the oplogs lack capacity, the oplogs may have turned over multiple times. This creates a gap between where a backup ends and an oplog starts.

If this oplog size check fails:

  • You cannot enable backups

  • Ops Manager displays the following:


    Insufficient oplog size: The oplog window must be at least <duration> hours over the last 24 hours for all members of replica set <deploymentName>. Please increase the oplog.

If possible, wait to start a backup until the oplog has had sufficient time to meet the size requirement.


Do not change the minimum oplog size unless you are certain smaller backups still provide useful backups.

MongoDB recommends only changing this value temporarily to permit a test backup job to execute. The minimum oplog size value should be reset to the default as soon as possible.

Understanding the risks given, you can start backups using this changed minimum value. Once you pass the 24 hour mark, you should reset this minimum value to preserve the sanity check for the global Ops Manager installation going forward.


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Frequently Asked Questions