rolling upgrade & elections

Parent: Atlas cluster tiers (M30) & major-version upgrade mechanics · Published reference · snapshot 2026-10-15

Depth-first rabbithole dossier for rolling upgrade & elections; source-anchored research pack.

These notes link each claim to its source. Some citations identify archived research reports that are no longer hosted on this site. A published reference means the content is available; it does not certify independent review or accuracy.Read the editorial policy and follow the sources before relying on a claim.

Definitions

[low] Live Migration and Mongosync are not supported on minor versions and will not work if the cluster uses Latest Version With Auto Upgrades. Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]

How it works

[medium] A major version upgrade in MongoDB Atlas requires at least one replica set election and uses a rolling update process to maintain cluster availability. Sources: https://www.mongodb.com/docs/atlas/tutorial/major-version-change.md, https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] To upgrade a sharded cluster, stop the balancer, upgrade the Config server replica set first, then upgrade the Shard replica sets in parallel using a rolling manner, and finally upgrade the last mongos, restarting the balancer afterwards. Sources: https://www.percona.com/blog/upgrade-process-of-percona-server-for-mongodb-replica-set-and-shard-cluster/ [source]
[low] An Atlas Core cluster on a minor version with Latest Version With Auto Upgrades can only switch to a major-version cadence when the next major version becomes available, such as remaining on the latest minor until MongoDB 9.0 is released if opting in during MongoDB 8.3. (verified as of 2026-10-15) Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] Atlas uses a rolling update strategy for maintenance and infrastructure operations, directing the primary node to step down to secondary state to trigger an election of a new primary. Sources: https://www.mongodb.com/docs/atlas/reference/faq/deployment.md [source]
[low] For replica set upgrades, start by upgrading secondaries one by one, then log into the Primary node and stepDown it, repeating the process once a new primary is elected. Sources: https://www.percona.com/blog/upgrade-process-of-percona-server-for-mongodb-replica-set-and-shard-cluster/ [source]
[medium] Always take a full backup of the database before performing an upgrade, and when making downgrades, remove incompatible features or update incompatible configuration settings. Sources: https://www.percona.com/blog/upgrade-process-of-percona-server-for-mongodb-replica-set-and-shard-cluster/, https://docs.percona.com/percona-operator-for-mongodb/update-major.html [source]

Problems, failure modes and limitations

[low] Atlas Infinite clusters always use Auto Upgrades with the Latest Version With Auto Upgrades option enabled, which cannot be disabled in the Atlas UI, and are updated about once a month without the option to select a specific MongoDB version. (verified as of 2026-10-15) Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]

Comparisons and alternatives

[medium] Elections on Atlas clusters typically complete within a few seconds, and unlike self-managed deployments, Atlas triggers replica set elections during routine maintenance operations performed on a rolling basis to avoid downtime. Sources: https://www.mongodb.com/docs/atlas/reference/faq/deployment.md, https://www.mongodb.com/docs/atlas/replica-set-rollbacks.md [source]

Facts and statements

[low] Atlas always upgrades clusters to the latest patch release of the specified major version, and for clusters on Latest Version With Auto Upgrades, it automatically upgrades to the latest available major or minor version and enables new features. Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] Only Atlas Core clusters support manual upgrading and downgrading of MongoDB versions; Atlas Infinite clusters run on Latest Version With Auto Upgrades and do not support manual version upgrades. Sources: https://www.mongodb.com/docs/atlas/tutorial/major-version-change.md [source]
[low] If a cluster uses Latest Version With Auto Upgrades, Atlas manages upgrades automatically, preventing users from performing manual upgrade procedures. Sources: https://www.mongodb.com/docs/atlas/tutorial/major-version-change.md [source]
[low] For Free and Flex clusters, Atlas automatically upgrades them and keeps them on a major version, currently MongoDB 8.0. (verified as of 2026-10-15) Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] During public preview, Atlas Infinite clusters run the latest MongoDB 9.x version using the Latest Version With Auto Upgrades release option. (verified as of 2026-10-15) Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] Atlas Core clusters can switch from Auto Upgrades to Manual Upgrades only in the window after a new major version releases, but can switch to Auto Upgrades at any time by modifying the cluster. Sources: https://www.mongodb.com/docs/atlas/atlas-versions.md [source]
[low] The Operator supports major upgrades within one major version at a time, such as from 7.0 to 8.0, requiring intermediate steps for larger jumps like upgrading Percona Server from 6.0 to 8.0 via 7.0. Sources: https://docs.percona.com/percona-operator-for-mongodb/update-major.html [source]
[low] To upgrade a cluster, you must have the Project Owner or higher role for the project. Sources: https://www.mongodb.com/docs/atlas/tutorial/major-version-change.md [source]
[low] Set the upgradeOptions.apply key in the deploy/cr.yaml Custom Resource manifest to <version>-recommended for Operator upgrades. Sources: https://docs.percona.com/percona-operator-for-mongodb/update-major.html [source]

Related concepts

upgrade — is a part of rolling upgrade & elections
rolling — is a part of rolling upgrade & elections
elections — is a part of rolling upgrade & elections

Children

No children recorded.

← the whole tree · 3D view· how to read this page