Storage System Asynchronous Cache Duplication for Write Speed
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Solution Overview
Problem
In storage systems, the maximum speed of data write is limited by cache access and duplication processes, particularly when compression and redundancy are involved, leading to delayed response times and potential data protection issues during device failures.
Innovation Solution
A storage system architecture that includes a first and second storage control unit with cache and buffer areas, where data is duplicated between these units upon write commands, allowing for asynchronous compression and storage, thereby reducing cache access and ensuring data protection even during device failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is compressed asynchronously after write completion, then data write speed is improved, but data protection reliability deteriorates
Solution Approach 1:
The patent performs compression on a copy of the data in the second cache area while the original data remains intact in the first cache area until the write is complete. This preliminary compression action on a duplicate allows speed optimization without compromising the reliability of the original data that is needed for the write response.
Solution Approach 2:
The patent divides the data into two separate cache areas (first cache area and second cache area) with different functions. The first cache area handles write operations and maintains data for reliability, while the second cache area performs compression operations. This segmentation allows both speed and reliability requirements to be satisfied simultaneously.
2Reliability
If data is compressed synchronously with write, then data protection reliability is improved, but data write speed deteriorates
Solution Approach 1:
The patent separates the compression operation from the write operation by using two distinct cache areas. The first cache area is dedicated to write operations and returns completion immediately, while the second cache area handles compression asynchronously. This segmentation eliminates the speed penalty of synchronous compression while maintaining reliability through the intact original data.
3Reliability
If cache access for duplication is performed, then data protection is improved, but maximum data write speed deteriorates
Solution Approach 1:
The patent performs the duplication to the second cache area as a preliminary action that occurs asynchronously after the write command is received. The first cache area returns write completion immediately without waiting for duplication to the second cache area, thus maintaining maximum write speed while still providing data protection through the duplicated data in the second cache area.
Data Source
AI summary
With omission of a duplication process of compressed data, a cache access frequency is reduced to improve throughput. A storage system includes first and second control units and a storage drive. Upon receiving a data write command, the first control unit stores data to be subjected to the write command in a first cache area of the first control unit, and stores the data in a second cache area of the second control unit to perform duplication, and upon completion of the duplication, the first control unit transmits a response indicating an end of write, performs a predetermined process on the data to be subjected to the write command, stores the data in a buffer area, reads the data stored in the buffer area, and transmits the read data to the storage drive.