Rolling upgrades in Elasticsearch - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a rolling upgrade in Elasticsearch?

A rolling upgrade is a method to update Elasticsearch nodes one at a time without stopping the entire cluster, allowing the cluster to stay online and serve requests during the upgrade.

beginner

Why is a rolling upgrade preferred over a full cluster restart?

Because it keeps the cluster available and responsive by upgrading nodes one by one, avoiding downtime and service interruption.

intermediate

What is the first step before starting a rolling upgrade in Elasticsearch?

Ensure the cluster health is green and all nodes are functioning properly to avoid issues during the upgrade.

intermediate

During a rolling upgrade, what happens to the node being upgraded?

The node is taken offline, upgraded to the new version, and then restarted before rejoining the cluster.

intermediate

What should you check after upgrading each node in a rolling upgrade?

Verify the node has rejoined the cluster and the cluster health remains green before proceeding to the next node.

What is the main benefit of a rolling upgrade in Elasticsearch?

A Requires cluster restart

B Faster upgrade process

C Upgrades all nodes simultaneously

D No downtime during upgrade

A rolling upgrade allows nodes to be upgraded one at a time, keeping the cluster available without downtime.

Before starting a rolling upgrade, what cluster state should you verify?

A Green

B Yellow

C Red

D Any state is fine

The cluster health should be green to ensure all shards are allocated and the cluster is stable.

During a rolling upgrade, what happens to the node being upgraded?

A It stays online and upgrades automatically

B It is taken offline, upgraded, then restarted

C It is removed permanently

D It upgrades without restart

The node is taken offline, upgraded, and restarted before rejoining the cluster.

What should you do after upgrading each node in a rolling upgrade?

A Immediately upgrade the next node

B Delete old data

C Check the node rejoined and cluster health is green

D Restart the entire cluster

You must verify the node rejoined the cluster and the cluster health is green before continuing.

Which Elasticsearch version upgrade method requires full cluster downtime?

A Full cluster restart

B Rolling upgrade

C Snapshot upgrade

D Hot swap upgrade

A full cluster restart requires stopping all nodes, causing downtime.

Explain the steps involved in performing a rolling upgrade in Elasticsearch.

Think about upgrading nodes one by one without stopping the whole cluster.

Why is it important to verify cluster health after upgrading each node during a rolling upgrade?

Consider what could happen if a node fails to rejoin.