Consistent Hashing easy
How do Virtual Nodes (VNodes) improve cluster balance?
- A By dynamically rotating the underlying hash algorithm based on the current observed system load and CPU usage.
- B By implementing a specialized transparent data compression layer that allows small nodes to store more physical keys.
- C By representing each physical server as multiple points (tokens) on the ring, effectively interleaving their owned ranges.
- D By creating a dedicated virtual machine for every individual key to ensure absolute isolation and processing priority.
Answer: C. By representing each physical server as multiple points (tokens) on the ring, effectively interleaving their owned ranges.
Virtual Nodes (VNodes) allow a single server to 'occupy' hundreds of random locations on the ring simultaneously. By breaking a server's responsibility into many small, interleaved slices, the cluster achieves much better statistical balance. If a server has 100 VNodes, its total ownership will likely converge to the average (1/N) of the ring space.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- In a 'Smart Client' architecture (e.g., modern Cassandra drivers), how does the client find the right node?
- When a new node (Node X) joins the ring, where does it acquire its initial data from?
- Google's Maglev hashing algorithm (used in their Network Load Balancers) differs from standard Consistent Hashing rings. How does it generate the lookup table?
- Virtual Nodes improve balance but increase metadata size (Memory). How does 'Multi-Probe Consistent Hashing' achieve good balance without VNodes?
- In the Chord DHT protocol (a P2P consistent hashing implementation), naive lookups are O(N). How does Chord optimize this to O(log N)?
- Which of these systems is a famous user of Consistent Hashing?