Virtual RAID Parity Allocation via Dynamic Disk Mapping
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Solution Overview
Problem
RAID4 experiences performance issues due to unsatisfactory load balancing and increased wear on the dedicated parity disk, while RAID5 and RAID6 attempt to address these but may not fully distribute wear effectively across all disks.
Innovation Solution
Implementing a virtual redundant array of independent disks (VRAID) that maps virtual disks and extents across a physical storage device pool, allowing for flexible distribution of normal and parity data, enabling load balancing and wear leveling by selecting less worn physical disks for parity storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parity data is stored on a dedicated parity disk in RAID4, then data security and redundancy are improved, but load balancing deteriorates and disk wear increases on the dedicated parity disk
Solution Approach 1:
The patent segments the parity storage function by dividing the storage system into virtual disks that are dynamically mapped to physical disks. Instead of dedicating one physical disk for parity, the parity data is distributed across multiple physical disks through virtualization, thereby segmenting the load and improving balance while maintaining data security.
Solution Approach 2:
The patent introduces virtual disks as an intermediary layer between the host system and physical disks. This virtualization layer mediates the mapping between virtual and physical storage resources, enabling flexible parity distribution across physical disks while presenting a unified storage interface to users, thus resolving the conflict between reliability and load balancing.
2Reliability
If parity data is updated more frequently than normal data, then data consistency and security are improved, but wear on storage elements increases
Solution Approach 1:
The patent applies local quality by dynamically assigning different physical disks for parity storage based on their wear status and performance characteristics. The virtualization layer can select less worn physical disks for parity data, thereby distributing the wear burden locally across different storage elements while maintaining overall data consistency through frequent parity updates.
Solution Approach 2:
The patent changes the parameter of parity storage location from fixed (dedicated parity disk) to dynamic (virtually mapped to different physical disks). By monitoring and adjusting the mapping between virtual and physical disks based on wear levels, the system maintains data consistency while extending the operational lifespan of storage elements through wear leveling.
3Duration of action of stationary object
If parity is distributed across physical disks in RAID5, then wear distribution is improved, but load balancing and performance may still be insufficient
Solution Approach 1:
The patent makes the storage system universal by enabling virtual disks to serve multiple functions - they can be dynamically mapped to different physical disks depending on the operation (read, write, parity update). This multi-functionality allows the system to optimize for wear distribution during writes while maintaining high performance during reads, overcoming the limitations of fixed RAID5 distribution.
Solution Approach 2:
The patent introduces dynamics by making the mapping between virtual and physical disks adaptable and changeable over time. The virtualization layer can dynamically adjust which physical disks store parity data based on current system conditions, wear levels, and performance requirements, thereby achieving both wear distribution and high performance that static RAID5 cannot provide.
Data Source
AI summary
Allocation of parity data storage extents for a virtual RAID is disclosed. A virtual RAID can be enabled by a virtual storage device pool (VSDP) mapped to a physical storage device pool (PSDP) that can comprise physical extents of physical disks. In an aspect, the physical disks can be co-located, remotely located, or combinations thereof. Mapping of the VSDP can enable allocation of virtual extents in a virtual RAID that can, for example, emulate a RAID4 while still providing parity data storage diversity that can, for example, emulate RAID5, RAID6, etc. Moreover, the disclosed subject matter can support proactive wear leveling, for example, based on historical storage of parity data via an extent, e.g., extents previously used to store parity data. Furthermore, the disclosed subject matter can support active wear leveling.