DEV Community

Vipul Kumar
Vipul Kumar

Posted on β€’ Originally published at knowledge-bytes.com

Hinted Handoff in System Design

πŸ”„ Definition β€” Hinted handoff is a technique used in distributed systems to improve write availability and ensure data durability when some nodes are temporarily unavailable.

πŸ“ Process β€” During a write operation, if a target node is down, the data is temporarily stored on another available node, along with a 'hint' indicating the intended recipient.

πŸ”„ Recovery β€” Once the target node is back online, the node holding the hint transfers the data to the original node, ensuring eventual consistency.

πŸ“ˆ Benefits β€” This method enhances system availability and fault tolerance by allowing writes to succeed even during partial outages.

⚠️ Limitations β€” Hinted handoff can lead to temporary inconsistencies and requires additional resources for storing and managing hints.

How It Works

πŸ” Detection β€” The system uses networking protocols like the gossip protocol to detect node failures.

πŸ“₯ Hint Storage β€” When a node is unavailable, the coordinator node stores the data and a hint indicating the intended node.

πŸ”„ Hint Transfer β€” Once the target node is back online, the coordinator node transfers the stored data to it.

πŸ› οΈ Consistency β€” This process ensures that the system eventually reaches a consistent state, with all nodes holding the correct data.

⏱️ Timing β€” Hints are typically stored for a limited time, such as three hours, to prevent data loss if a node is permanently down.

Advantages and Disadvantages

πŸ‘ High Availability β€” Hinted handoff allows systems to maintain high write availability even during node failures.

πŸ”„ Fault Tolerance β€” It increases fault tolerance by ensuring data is not lost during temporary outages.

⏳ Eventual Consistency β€” The system eventually reconciles all hinted writes, maintaining data consistency.

⚠️ Temporary Inconsistency β€” There can be temporary inconsistencies while data is held by a hinted node.

πŸ’Ύ Resource Overhead β€” Managing hints requires additional storage and computational resources.

Real-World Examples

🌐 Apache Cassandra β€” Utilizes hinted handoff to optimize cluster consistency and manage node failures.

☁️ Amazon DynamoDB β€” Employs hinted handoff to ensure high availability and eventual consistency in its NoSQL database service.

πŸ”„ Use Cases β€” Commonly used in distributed systems requiring high availability and fault tolerance.

πŸ“ˆ Performance β€” Helps maintain system performance during network partitions and node failures.

πŸ”§ Implementation β€” Requires careful implementation to manage hints and ensure eventual data consistency.

Read On LinkedIn | WhatsApp

Follow me on: LinkedIn | WhatsApp | Medium | Dev.to | Github

Image of Timescale

πŸš€ pgai Vectorizer: SQLAlchemy and LiteLLM Make Vector Search Simple

We built pgai Vectorizer to simplify embedding management for AI applicationsβ€”without needing a separate database or complex infrastructure. Since launch, developers have created over 3,000 vectorizers on Timescale Cloud, with many more self-hosted.

Read full post β†’

Top comments (0)

Image of Docusign

πŸ› οΈ Bring your solution into Docusign. Reach over 1.6M customers.

Docusign is now extensible. Overcome challenges with disconnected products and inaccessible data by bringing your solutions into Docusign and publishing to 1.6M customers in the App Center.

Learn more

πŸ‘‹ Kindness is contagious

Please leave a ❀️ or a friendly comment on this post if you found it helpful!

Okay