Data Object Ownership Migration in Distributed Systems
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Solution Overview
Problem
In network environments where data objects are replicated across computing nodes, the migration of ownership from one node to another can be complicated by the inherent characteristics of networks, leading to conflicts and inefficiencies, such as different nodes having different information about the data object owner, resulting in inconsistent forwarding of requests.
Innovation Solution
The system employs a hand-off message to initiate ownership transfer and a claim message to confirm the transfer, ensuring that all nodes halt processing and queue requests, allowing seamless transition of ownership from the current owner to a new node, while preserving the order of requests in some scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ownership migration is initiated without coordination messages, then the migration process is simpler and faster, but network inconsistencies occur where different nodes have different information about the data object owner
Solution Approach 1:
The hand-off message is sent in advance to notify other nodes about the upcoming ownership migration before it actually occurs. This preliminary notification allows nodes to prepare for the change, ensuring they will have consistent information about the new owner when the migration completes, thus preventing network inconsistencies while maintaining efficient migration speed.
2Productivity
If nodes continue processing requests during ownership migration, then processing efficiency is maintained, but request ordering conflicts and inconsistencies occur
Solution Approach 1:
The hand-off message includes an instruction to other nodes to halt processing of requests for the data object before the ownership migration is complete. This preliminary preventive action stops potential request ordering conflicts from occurring in the first place, ensuring consistency while allowing the system to resume normal high-speed processing once the migration is finalized.
3Stability of the object's composition
If all nodes halt processing during ownership migration, then request order consistency is maintained, but network bandwidth is consumed by suspension messages
Solution Approach 1:
The hand-off message serves multiple functions simultaneously: it notifies nodes of the upcoming ownership change, instructs nodes to halt processing to maintain consistency, and initiates the migration process. By combining these functions into a single message, the system maintains request order consistency without consuming additional network bandwidth for separate suspension notifications.
4Productivity
If the original owner node stops operating after ownership transfer, then resource utilization is optimized, but fault tolerance is reduced
Solution Approach 1:
The claim message acts as an intermediary confirmation mechanism. The new owner node sends this message to confirm it has successfully assumed ownership, allowing the original owner node to gracefully stop operating with certainty that ownership has been transferred. This confirmation process ensures fault tolerance by verifying the migration completed successfully before resources are released.
Data Source
AI summary
A computing system implemented method is disclosed for reassigning ownership of a data object between computing nodes. A first computing node having control of a data object transmits a hand-off message indicating control of the data object is being transferred to a second computing node. The first computing node queues requests received at the first computing node relating to the data item. A third computing node that interacts with the data object receives the hand-off message and, in response, delays transmitting requests relating to the data object. When the second computing node receives the hand-off message, it transmits a message claiming control of the data object. In response to the message claiming control, the first computing node and the third computing node transmit their queued requests relating to the data item to the second computing node.