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Upgrade a Standalone to 4.4

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Warning

When upgrading a MongoDB 4.2-series deployment containing MongoDB 3.0 metadata to a 4.4-series deployment, you must upgrade to MongoDB 4.4.1 or later. You cannot successfully upgrade a deployment containing MongoDB 3.0 metadata to MongoDB 4.4.0 without serious risk of downtime.

For more information, see WT-6623.

Familiarize yourself with the content of this document, including thoroughly reviewing the prerequisites, prior to upgrading to MongoDB 4.4.

The following steps outline the procedure to upgrade a standalone mongod from version 4.2 to 4.4.

If you need guidance on upgrading to 4.4, MongoDB offers major version upgrade services to help ensure a smooth transition without interruption to your MongoDB application.

Upgrade Recommendations and Checklists

When upgrading, consider the following:

Upgrade Version Path

To upgrade an existing MongoDB deployment to 4.4, you must be running a 4.2-series release.

To upgrade from a version earlier than the 4.2-series, you must successively upgrade major releases until you have upgraded to 4.2-series. For example, if you are running a 4.0-series, you must upgrade first to 4.2 before you can upgrade to 4.4.

Preparedness

Before beginning your upgrade, see the Compatibility Changes in MongoDB 4.4 document to ensure that your applications and deployments are compatible with MongoDB 4.4. Resolve the incompatibilities in your deployment before starting the upgrade.

Before upgrading MongoDB, always test your application in a staging environment before deploying the upgrade to your production environment.

Downgrade Consideration

Once upgraded to 4.4, if you need to downgrade, we recommend downgrading to the latest patch release of 4.2.

Downgrade Floor

If you need to downgrade form version 4.4, downgrade to 4.2.6 or a later version. You cannot downgrade to 4.2.5 or an earlier version.

Prerequisites

Confirm Clean Shutdown

Prior to upgrading, confirm that your mongod instance was cleanly shut down.

Feature Compatibility Version

The 4.2 instance must have featureCompatibilityVersion set to "4.2". To check featureCompatibilityVersion:

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

The operation should return a result that includes "featureCompatibilityVersion" : { "version" : "4.2" }.

To set or update featureCompatibilityVersion, run the following command:

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db.adminCommand( { setFeatureCompatibilityVersion: "4.2" } )

For more information, see setFeatureCompatibilityVersion.

Consider Converting to Replica Set

Prior to upgrading, consider converting your standalone deployment to a replica set. Replica sets are the recommended deployment configuration for MongoDB.

Download 4.4 Binaries

Via Package Manager

If you installed MongoDB from the MongoDB apt, yum, dnf, or zypper repositories, you should upgrade to 4.4 using your package manager.

Follow the appropriate 4.4 installation instructions for your Linux system. This will involve adding a repository for the new release, then performing the actual upgrade process.

Manually

If you have not installed MongoDB using a package manager, you can manually download the MongoDB binaries from the MongoDB Download Center.

See 4.4 installation instructions for more information.

Upgrade Process

1

Replace existing 4.2 binaries with the 4.4 binaries.

Shut down your mongod instance. Replace the existing binary with the 4.4 mongod binary.

Restart your deployment with the 4.4 mongod.

2

Enable backwards-incompatible 4.4 features.

At this point, you can run the 4.4 binaries without the 4.4 features that are incompatible with 4.2.

To enable these 4.4 features, set the feature compatibility version (FCV) to 4.4.

Tip

Enabling these backwards-incompatible features can complicate the downgrade process since you must remove any persisted backwards-incompatible features before you downgrade.

It is recommended that after upgrading, you allow your deployment to run without enabling these features for a burn-in period to ensure the likelihood of downgrade is minimal. When you are confident that the likelihood of downgrade is minimal, enable these features.

Run the setFeatureCompatibilityVersion command against the admin database:

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db.adminCommand( { setFeatureCompatibilityVersion: "4.4" } )

This command must perform writes to an internal system collection. If for any reason the command does not complete successfully, you can safely retry the command as the operation is idempotent.

Additional Upgrade Procedures

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