Storage Control Device Unaligned Write Handling via Media Cache Thresholds
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Solution Overview
Problem
When a higher-level device causes a hard disk drive (HDD) to execute a read-modify-write process, the performance of writing unaligned data is reduced, especially if the media cache does not have an available region, leading to inefficiencies and potential HDD lifespan reduction due to unnecessary performance testing.
Innovation Solution
A storage control method that dynamically switches between the storage control device and HDDs for executing the read-modify-write process based on media cache usage statuses, optimizing the process by generating aligned data when necessary and avoiding insufficient cache conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the storage executes the read-modify-write process, then the storage can handle unaligned data writes, but the response performance is reduced when media cache available capacity is insufficient
Solution Approach 1:
The patent dynamically switches the execution location of the read-modify-write process between the storage control device and the storage device based on real-time media cache availability. When cache is sufficient, storage executes RMW; when cache is insufficient, storage control device executes RMW. This dynamic adaptation resolves the contradiction between handling unaligned data and maintaining response performance.
Solution Approach 2:
The storage control device acts as an intermediary that receives write requests, checks media cache availability, and decides whether to execute RMW itself or delegate to storage. This intermediary role allows the system to maintain high response performance by handling RMW operations when cache is insufficient, while still supporting unaligned data writes.
2Speed
If the storage control device executes the read-modify-write process, then the response performance is improved, but the device complexity increases
Solution Approach 1:
The storage device self-manages its media cache by monitoring its own available capacity and autonomously deciding whether to execute RMW operations or delegate to the storage control device. This self-service approach reduces the burden on the storage control device and simplifies overall system complexity while maintaining high response performance.
Solution Approach 2:
The patent changes the execution parameter of RMW operations based on the media cache availability threshold. When available capacity exceeds the threshold, storage executes RMW; otherwise, storage control device executes RMW. This parameter-based decision simplifies control logic by using a clear threshold criterion rather than complex adaptive algorithms.
3Loss of time
If performance testing is executed continuously, then the processing speed can be measured, but the HDD lifespan is reduced due to unnecessary testing
Solution Approach 1:
Instead of continuous performance testing, the patent implements periodic testing only when cache availability status changes. The storage control device measures processing speeds at these periodic intervals and caches the results, avoiding unnecessary continuous testing that would reduce HDD lifespan while still maintaining accurate performance data for decision-making.
Solution Approach 2:
The patent performs performance testing in advance and stores the measured processing speeds for future reference. By pre-measuring and caching performance data, the system avoids repeated testing under similar conditions, reducing unnecessary HDD operations while maintaining accurate performance measurement for optimization decisions.
Data Source
AI summary
A storage control method executed by a processor included in a storage control device, the storage control device being coupled to a storage including a media cache, the storage being capable of executing a read-modify-write process, the storage control method includes receiving, from the storage, usage information indicating a usage status of the media cache; receiving a write request to write an unaligned data in the storage; transmitting an unaligned data corresponding to the write request to the storage, when the usage information indicates that an available capacity of the media cache is equal to or smaller than a threshold; generating an aligned data from the unaligned data corresponding to the write request by executing the read-modify-write process within the storage control device, when the usage information indicates that the available capacity of the media cache is larger than the threshold; and transmitting the generated aligned data to the storage.