Mongodb version upgrade and downgrade

MongoDB Atlas
,
1

Hello!

I recently upgraded a mongo atlas cluster(M10) in stage from version 4.4 to 5.0. I checked right away if i can downgrade to 4.4(in case there is an issue in production and there is the need to downgrade) and i could not find a downgrade option(in the same atlas ui . I did not change the FCV after upgrading nor did i use a new feature from version 5.0.

When i ran:

db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

I get the following output:

{
    "getParameter" : 1.0,
    "featureCompatibilityVersion" : 1.0,
    ...
}

I checked the following guide, https://www.mongodb.com/docs/manual/release-notes/5.0-downgrade-replica-set/ and I could not find something helpful.

Am i doing something wrong? Is there a way to downgrade an mongodb atlas cluster?
We are planning to upgrade to version 7.0 so having the option to downgrade in case something goes wrong would be fantastic.

Thanks a lot!

2

After upgrading the MongoDB major version, you will not be able to downgrade to previous versions.

Your rollback to 4.4 would be to use Cloud Backup to restore to a new 4.4 cluster using a point before the upgrade.

Taking a snapshot before you execute the upgrade may speed this up if you have a particularly busy cluster.

3

Thanks a lot for the quick answer!

Yes the cluster is busy in general.
One more question. I saw through the Atlas UI that when i tried to restore a snapshot it said that the cluster will be unavailable. That means that there will be a downtime(when upgrading, considering the rolling mode this was not an issue)

4

Correct. The target cluster for the restore will have downtime.

Best is to run the apps in a staging environment and perform all required testing before upgrading the prod cluster so the rollback is hopefully not needed at all.

1 Like