Storage Controller Parity Staging to Cut Write Load
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Solution Overview
Problem
Conventional data storage systems using RAID 5 configurations face challenges in improving the reliability of a single data storage apparatus while maintaining cost-effectiveness, as the large amount of parity data written slows down user data writing speed and reduces the storage medium's lifespan due to frequent rewriting.
Innovation Solution
The solution involves a data storage apparatus with a first data-storage unit for parity data and a second data-storage unit for user and parity data, where parity data is updated and then written into the second unit at specific intervals, reducing the writing load on the storage medium compared to user data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parity data is frequently written to ensure data reliability, then reliability is improved, but the storage medium's lifespan is reduced due to frequent rewriting
Solution Approach 1:
The storage system is segmented into multiple storage devices, with dedicated parity storage areas in each device. This segmentation allows parity data to be distributed and updated locally without requiring frequent rewriting across the entire storage array, thereby reducing wear on individual storage media while maintaining reliability through distributed redundancy.
Solution Approach 2:
The system performs preliminary actions by maintaining up-to-date parity data in memory or fast storage before actual data writing operations. When data is written, the corresponding parity data is already prepared and can be immediately committed, reducing the need for repeated parity rewriting operations and extending storage medium lifespan.
2Reliability
If parity data is written with every user data update to maintain reliability, then reliability is improved, but user data writing speed deteriorates
Solution Approach 1:
By segmenting the storage system into multiple devices with distributed parity storage, the system allows parallel writing operations. User data can be written to one device while parity data is simultaneously updated in another, eliminating the sequential dependency that slows down writing speed while maintaining reliability through distributed redundancy.
Solution Approach 2:
The system performs preliminary parity calculation and preparation in advance, storing parity data in memory or fast storage before actual data writing. This preliminary action ensures that when user data is written, the corresponding parity data is already ready, eliminating the time penalty of real-time parity calculation and commitment, thus improving writing speed without compromising reliability.
Data Source
AI summary
According to one embodiment, a controller controls writing into and reading from a storage apparatus that includes a first data-storage unit and a second data-storage unit. The second data-storage unit stores user data and parity data of the user data. The first data-storage unit stores the parity data. The controller includes a parity updating unit and a parity writing unit. When parity data is updated, the parity updating unit writes the updated parity data into the first data-storage unit. When a certain requirement is satisfied, the parity writing unit reads the parity data written in the first data-storage unit, and writes the parity data thus read into the second data-storage unit.