CASSANDRA Operations and Administration

Question 1

What does 'nodetool repair' do in Cassandra?

Accepted Answer

Synchronizes replicas by comparing and streaming missing data between nodes

Answer

Rewrites corrupt SSTables

Answer

Rebuilds secondary indexes

Answer

Restores data from a snapshot

Question 2

What does the 'nodetool drain' command do before a node shutdown?

Accepted Answer

Flushes all MemTables, stops accepting writes, and drains the CommitLog so the node can be safely stopped

Answer

Removes the node from the ring

Answer

Decommissions the node and rebalances tokens

Answer

Clears the key cache and row cache

Question 3

What does 'nodetool cleanup' do after adding a new node to a Cassandra cluster?

Accepted Answer

Deletes data from existing nodes that no longer falls within their token ranges after rebalancing

Answer

Removes tombstones from all SSTables

Answer

Compacts all SSTables on the new node

Answer

Rebuilds materialized views on all nodes

Question 4

What is the purpose of 'nodetool rebuild' command?

Accepted Answer

Streams data for all token ranges from a specified data center, used when adding a new DC

Answer

Rebuilds SSTables from the CommitLog after corruption

Answer

Rebuilds secondary indexes for all tables

Answer

Replays hinted handoff hints

Question 5

How can you monitor Cassandra metrics using industry-standard monitoring tools?

Accepted Answer

Cassandra exposes metrics via JMX, which can be scraped by tools like Prometheus via a JMX exporter

Answer

Cassandra exposes metrics only via its REST API

Answer

Metrics are only available through cqlsh system tables

Answer

Cassandra pushes metrics to a CloudWatch endpoint automatically

Question 6

What does 'nodetool move' do in Cassandra?

Accepted Answer

Changes the token assignment of the current node to rebalance data distribution

Answer

Migrates all data to a new data center

Answer

Moves CommitLog files to a new directory

Answer

Transfers ownership of all token ranges to a peer node