Persistent Memory Operation Forwarding to Prevent Stale Data
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Solution Overview
Problem
Existing storage systems face challenges in maintaining data consistency and reducing latency when using persistent memory, as data in the persistent memory tier can become stale relative to the storage file system, leading to inefficiencies and potential inconsistencies.
Innovation Solution
Implement a forwarding mechanism that directs certain operations, such as multi-block sequential writes and partial writes, directly to the storage file system while ensuring the persistent memory maintains the authoritative copy of data, thereby reducing latency and preserving data consistency by removing stale data from the persistent memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is stored in persistent memory tier, then access latency is reduced, but data consistency with storage file system deteriorates
Solution Approach 1:
The patent introduces a forwarding mechanism as an intermediary between the persistent memory tier and storage file system. This mechanism selectively forwards operations (such as multi-block sequential writes and partial writes) to the storage file system while maintaining the persistent memory as the authoritative copy for read operations, thus resolving the contradiction between fast access and data consistency
Solution Approach 2:
The patent applies different handling strategies to different types of operations: read operations access the persistent memory directly for fast access, while specific write operations (multi-block sequential writes, partial writes) are forwarded to the storage file system to maintain consistency. This local differentiation allows the system to optimize for both speed and reliability in different contexts
2Speed
If operations are executed through persistent memory file system, then read performance is improved, but complexity of operation handling increases
Solution Approach 1:
The patent extracts complex operation handling from the persistent memory file system by forwarding specific operations (multi-block sequential writes, partial writes) to the storage file system. This extraction reduces the operational complexity within the persistent memory tier while preserving its read performance advantages
3Speed
If persistent memory is used for data storage, then access speed is improved, but stale data may be served to clients
Solution Approach 1:
The patent implements a feedback mechanism through the forwarding process, where operations are selectively forwarded to the storage file system based on their type. This feedback loop ensures that when data needs to be updated, the storage file system is notified and can provide updated data, preventing stale data from being served to clients while maintaining fast access through the persistent memory for read operations
Data Source
AI summary
Techniques are provided for forwarding operations to bypass persistent memory. A modify operation, targeting an object, may be received at a persistent memory tier of a node. If a forwarding policy indicates that forwarding is not enabled for the modify operation and the target object, then the modify operation is executed through a persistent memory file system. If the forwarding policy indicates that forwarding is enabled for the modify operation and the target object, then the modify operation is forwarded to a file system tier as a forwarded operation for execution through a storage file system.