Question about resolving Replication Oplog Window alert

Ops and Admin
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I have an alert on my Atlas cluster warning me that our Maximum Op log window is falling below one hour at peak write times.

From the configuration screen for the cluster I found the docs about what that means here https://www.mongodb.com/docs/atlas/cluster-additional-settings/#set-minimum-oplog-window

Because our cluster is set to scale automatically we don’t see the Op log size option in the cluster config, we see the ’ Set Minimum Oplog Window’ option, we have not changed this but the value in there is Zero, the docs say the default is 24 hours.

Could anyone help me answer these two questions:

  1. Is Zero for Set Minimum Oplog Window equivalent to default? (ie does Zero mean the window is already 24 hours?)
  2. If our window is already 24 hours and our cluster is set to autoscale, can I do anything to increase the size of the oplog and stop the replication window from getting into the danger zone?

Thanks for any and all help trying to figure this out.

Josh Butterworth

2

Hi @Josh_Butterworth

This should be set to at least 24hrs. But if it says 0 it is 0 which reverts to the Maximum Oplog Size

This cluster may not have been created with Auto-Expand Storage enabled so the Minimum Oplog Window would not have been set.

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Thank you Chris I will update that setting now

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