Tiered Storage Access Count Correction for Copy-on-Write
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Solution Overview
Problem
In tiered storage systems, the copy-on-write operation can lead to incorrect access count management, causing data that should be stored on high-speed storage devices to be relocated to low-speed storage devices, reducing user convenience and system performance.
Innovation Solution
A correction support unit is introduced to manage access counts by carrying over access counts from the original logical block to the new logical block during copy-on-write operations, ensuring accurate tiering based on access frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copy-on-write operation is implemented in tiered storage system, then data integrity and security are improved, but access count management accuracy deteriorates
Solution Approach 1:
The patent segments the access count management by introducing separate counters: a first counter that records access counts before copy-on-write operations, and a second counter that records access counts after operations. This segmentation allows the system to track access patterns accurately despite the complexity of copy-on-write operations, resolving the contradiction between maintaining data integrity through copy-on-write and preserving access count accuracy.
Solution Approach 2:
The patent implements feedback mechanisms where the storage controller continuously monitors and updates access counts. By comparing the first access count (before copy-on-write) with the second access count (after copy-on-write), the system receives feedback on actual access patterns and adjusts tiering decisions accordingly, maintaining measurement precision while preserving the reliability benefits of copy-on-write operations.
2Reliability
If access count is divided between old area and new area during copy-on-write, then data security is improved, but tiering accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by recording the access count in a first counter before the copy-on-write operation occurs. This preliminary recording captures the access pattern intent, which is then used to determine appropriate tiering decisions. By establishing the access count baseline before security-related copy operations, the system maintains tiering accuracy while still implementing the security benefits of copy-on-write.
Solution Approach 2:
The patent introduces an intermediary mechanism (the first counter) that mediates between the copy-on-write security operations and the tiering accuracy requirements. This intermediary records access counts independently of the copy operations, allowing the system to maintain accurate tiering decisions based on genuine access patterns rather than being distorted by security-related data copying activities.
3Reliability
If copy-on-write operation is used, then system reliability is improved, but user convenience deteriorates due to incorrect data relocation
Solution Approach 1:
The patent uses feedback from comparing first and second access counts to ensure data is relocated to appropriate tiers based on actual usage patterns. This feedback mechanism prevents incorrect relocation that would occur with simple access count division, thereby maintaining user convenience while preserving the reliability improvements from copy-on-write operations. Users experience accurate data placement that reflects their actual access behavior.
Solution Approach 2:
The patent changes the parameter tracking approach by introducing separate counter mechanisms and comparing access counts at different stages (before and after copy-on-write). This parameter change enables the system to distinguish between security-related copying and actual user access patterns, ensuring data is relocated based on genuine usage and maintaining user convenience while preserving system reliability.
Data Source
AI summary
According to one embodiment, a tiered storage system includes a tiered storage device and a computer. The computer uses the tiered storage device, and includes a file system and a correction support unit. If an access request from an application is a write request to request overwriting of data, the file system executes a copy-on-write operation. The correction support unit causes the storage controller to carry over an access count manacled by the storage controller and associated with the logical block address of a copy source in the copy-on-write operation, to an access count associated with the logical block address of a copy destination in the copy-on-write operation.