ElasticSearch ElasticSearch Cluster Management & Administration 3

Question 1

Which Elasticsearch API is used to manually reroute a shard to a different node in the cluster?

Accepted Answer

POST /_cluster/reroute

Answer

POST /_cluster/reroute accepts commands like move, allocate_replica, and cancel to manually control shard placement across nodes.

Question 2

What is the recommended way to gracefully decommission a node from an Elasticsearch cluster without losing data?

Accepted Answer

Set cluster.routing.allocation.exclude._name to the node's name

Answer

Setting cluster.routing.allocation.exclude._name instructs Elasticsearch to evacuate all shards from that node before removal, ensuring no data is lost.

Question 3

What is the primary purpose of Elasticsearch Index Lifecycle Management (ILM)?

Accepted Answer

Automatically transitioning indices through hot, warm, cold, and delete phases based on policies

Answer

ILM automates the entire lifecycle of an index — transitioning it through hot, warm, cold, frozen, and delete phases — based on configurable age or size policies.

Question 4

What information does the GET /_cat/shards API provide?

Accepted Answer

Per-shard details including state, size, document count, and node assignment

Answer

GET /_cat/shards returns a human-readable table showing each shard's state (STARTED, INITIALIZING, UNASSIGNED), size, document count, and the node it is assigned to.

Question 5

What defines a 'hot-warm' architecture in Elasticsearch?

Accepted Answer

Using SSD nodes for recent data and HDD nodes for older data to balance performance and cost

Answer

Hot-warm architecture assigns recent, frequently accessed data to fast SSD nodes (hot) and moves older, less-accessed data to cheaper HDD nodes (warm), optimizing cost and performance.

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ElasticSearch ElasticSearch Cluster Management & Administration 3