Storage Controller Performance Zone Allocation
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Solution Overview
Problem
Storage systems face performance variations across logical volumes due to differences in read and write media rates on rotating magnetic disks and hybrid storage devices, leading to issues like data starvation and excessive read/write head movement.
Innovation Solution
A storage controller identifies and allocates storage from multiple performance zones with varying criteria across logical volumes, ensuring uniform performance access by distributing storage from high-speed and low-speed zones, thereby normalizing storage performance across multiple logical volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If storage space is allocated sequentially from the beginning of the disk, then the allocation process is simple, but performance varies significantly across logical volumes due to radial position differences
Solution Approach 1:
The patent segments the storage device into multiple performance zones based on radial position, with each zone having characteristic read/write speeds. Instead of treating the disk as a uniform space, it divides it into distinct segments (zones) that are then distributed across logical volumes to ensure each volume receives a balanced mix of high-performance and standard-performance storage space.
Solution Approach 2:
The patent applies local quality by assigning different performance characteristics to different radial zones of the disk. Each zone is characterized by its specific read/write speeds, and the allocation process deliberately distributes these zones across multiple logical volumes so that each volume experiences similar average performance, rather than allowing sequential allocation to create performance disparities.
2Quantity of substance
If multiple logical volumes are created on a single storage device, then storage capacity is efficiently utilized, but performance starvation occurs for volumes allocated to slower radial zones
Solution Approach 1:
The storage device is segmented into performance zones that are then distributed across logical volumes. This segmentation ensures that no single logical volume is confined to slow radial zones, thereby preventing performance starvation while maintaining efficient storage capacity utilization across all volumes.
Solution Approach 2:
The patent changes the allocation parameter from sequential (linear) allocation to zoned allocation based on radial position. By measuring and characterizing the read/write speeds at different radial positions and using this information to guide allocation, the system transforms the allocation strategy to balance performance across volumes while maximizing storage utilization.
3Adaptability or versatility
If read/write heads move frequently to serve different logical volumes, then data access flexibility is improved, but excessive head movement increases access time and reduces system responsiveness
Solution Approach 1:
The patent performs preliminary characterization of the storage device to identify performance zones and their read/write speeds before allocation. This preliminary action allows the system to pre-plan the distribution of zones across logical volumes, optimizing the layout to minimize head movement while maintaining access flexibility. The allocation is done in advance with full knowledge of performance characteristics.
Solution Approach 2:
The patent replaces the traditional mechanical sequential allocation approach with an intelligent allocation system that uses measured performance data to guide zone distribution. Instead of relying on simple mechanical rules (allocate from current head position), the system substitutes a data-driven allocation mechanism that optimizes for both flexibility and reduced head movement.
4Speed
If flash memory is used as cache in hybrid storage devices, then read performance is improved, but write performance may be bottlenecked by flash memory speed limiting the rotational media
Solution Approach 1:
The patent applies local quality by characterizing different radial zones of the rotational media with their specific read/write speed profiles. Instead of treating the hybrid storage device as a uniform system, it identifies zones where the rotational media can operate at full speed without being bottlenecked by flash memory write speeds, and allocates logical volume portions to these zones to optimize write throughput.
Solution Approach 2:
The patent changes the allocation strategy to consider both read and write speed parameters at different radial positions. By measuring actual read/write speeds in different zones and using this data to guide allocation, the system optimizes for balanced performance rather than just read speed, ensuring that write operations are not bottlenecked by flash memory limitations in high-speed zones.
Data Source
AI summary
Methods and structure are disclosed for normalizing storage performance across a plurality of logical volumes. One embodiment is a storage controller. The storage controller is adapted to couple with a plurality of host systems and a storage device. The storage controller is adapted to receive one or more requests to create logical volumes for the plurality of hose systems, and adapted to identify a plurality of performance zones for storage areas of the storage device. The performance zones exhibit different performance criteria for one or more of: reading data from the storage device and writing data to the storage device. The storage controller is further adapted to allocate storage from each of the plurality of performance zones for each of the plurality of logical volumes such that the performance criteria for accessing the storage device is distributed substantially uniformly across the plurality of logical volumes.