Remote Storage Location Cache Invalidation for Read Latency
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Solution Overview
Problem
Conventional networked storage systems experience latency in processing read requests due to the need for forwarding requests between storage nodes, which can impact performance, especially in SAN environments.
Innovation Solution
Implementing a remote storage location cache (R-SLC) that allows a secondary storage node to cache storage location information for data stored by a primary node, enabling it to process read requests directly without forwarding them, along with a remote hash data structure (R-HAC) for attribute management and a heartbeat mechanism for cache control, reducing latency and handling race conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional storage system forwards read requests between storage nodes, then data can be accessed from multiple paths, but processing latency increases
Solution Approach 1:
The system performs preliminary actions by creating cache entries in the R-SLC before read requests arrive. When a write operation occurs on the primary node, the system proactively caches the data location information in the secondary node's R-SLC. This preliminary caching enables the secondary node to immediately serve read requests without waiting for primary node responses, thus reducing latency while maintaining data availability through multiple access paths.
2Speed
If a remote storage location cache is implemented to reduce latency, then read request processing speed improves, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary mechanism - the invalidation request system - that mediates between the primary and secondary nodes. When data is modified on the primary node, an invalidation request is sent to the secondary node to invalidate corresponding cache entries. This intermediary invalidation mechanism simplifies cache management by providing a centralized control method, avoiding the need for complex distributed cache coherence protocols while maintaining data consistency.
Solution Approach 2:
The system implements feedback through invalidation requests that flow from the primary node to the secondary node. When the primary node detects data modifications, it sends feedback in the form of invalidation requests to the secondary node, which then updates its R-SLC accordingly. This feedback mechanism ensures cache consistency without requiring complex peer-to-peer communication or centralized coordination, simplifying the overall system architecture.
3Productivity
If cache entries are maintained in the remote storage location cache, then read requests can be processed directly, but data consistency may be compromised
Solution Approach 1:
The system applies preliminary anti-action by proactively invalidating cache entries before they could become stale. When the primary node modifies data, it immediately sends invalidation requests to the secondary node to clear corresponding R-SLC entries. This preliminary invalidation prevents the cache from serving outdated data, ensuring data consistency is maintained while still allowing the cache to provide high-speed access for valid entries.
Data Source
AI summary
Methods and systems for a networked storage system are provided. One method includes: receiving, by a first storage node, a request to modify data stored using a logical storage object presented by the first storage node, the first storage node communicating with a second storage node configured as a failover partner of the first storage node; transmitting, by the first storage node, an invalidation request to the second storage node to invalidate an entry in a storage location cache of the second storage node, the entry indicating a storage location where data is stored by the first storage node, before modification; and responding, by the first storage node, to the request after modifying the data and upon receiving a response from the second storage node indicating successful invalidation of the entry.