Dynamic Segment Height Selection for Heterogeneous RAID Storage
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Solution Overview
Problem
In storage systems with heterogeneous solid-state storage devices having different erase block sizes, the existing methods for selecting segment heights are suboptimal, leading to inefficiencies such as pinned erase blocks and reduced storage capacity due to mismatched erase block sizes, especially when drives with different capacities and programming modes are replaced over time.
Innovation Solution
A storage controller dynamically selects a segment height based on the erase block sizes of the storage devices, using methods like the least common multiple, smallest, or largest erase block size to optimize storage capacity and reduce programming time, with the selected segment height stored in metadata for dynamic adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If homogeneous erase blocks of the same size are used in RAID stripes, then storage memory usage is efficient and data recovery is simplified, but the system cannot accommodate heterogeneous storage devices with different erase block sizes
Solution Approach 1:
The patent dynamically changes the segment height parameter based on the erase block sizes of the storage devices. The controller determines the segment height by calculating the least common multiple (LCM) of the erase block sizes, allowing the system to adapt to heterogeneous devices while maintaining efficient RAID stripe management.
Solution Approach 2:
The patent introduces dynamic segment height selection that can adapt to changing storage device configurations. The controller dynamically determines the appropriate segment height for each RAID stripe based on the specific erase block sizes of the devices involved, enabling flexible accommodation of heterogeneous storage devices.
2Adaptability or versatility
If segment height is selected based on the largest erase block size, then all devices can be accommodated, but storage capacity is reduced due to pinned erase blocks
Solution Approach 1:
The patent calculates the segment height as the least common multiple (LCM) of all erase block sizes in the storage device group. This mathematical approach ensures that the segment height is divisible by all individual erase block sizes, eliminating pinned erase blocks while maintaining compatibility with heterogeneous devices and maximizing storage capacity utilization.
3Productivity
If dynamic segment height selection is implemented, then storage capacity and programming efficiency are improved, but controller complexity increases
Solution Approach 1:
The patent performs preliminary determination of the segment height during the RAID stripe creation process. The controller calculates the LCM of erase block sizes and establishes the segment height before data programming begins, avoiding the need for complex real-time adjustments during operations and simplifying the overall control logic.
Data Source
AI summary
A system includes a solid-state storage array having a plurality of solid-state storage devices and a storage controller coupled to the solid-state storage array, the storage controller including a processing device, the processing device to select a segment height based on erase block sizes of the plurality of solid-state storage devices. The processing device is further to program a data segment using the segment height to a data stripe across two or more of the plurality of solid-state storage devices and store the segment height in metadata associated with the data segment.