RAID Extent Allocation for Disk Management Flexibility
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Solution Overview
Problem
Traditional RAID technologies face inefficiencies in disk management, particularly during extent reallocation and data migration, leading to delayed operations and reduced flexibility in creating new RAIDs due to unnecessary migration of invalid data and the need for extensive reallocation processes.
Innovation Solution
The implementation of on-demand extent allocation, where extents are selected and mapped only when a stripe is ready for data writing, allowing for flexible allocation and reducing the need for pre-allocation across all RAID stripes, thereby improving performance and reducing unnecessary data migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional RAID performs data writing evenly across all disks, then data distribution is uniform, but disk management flexibility is reduced and unnecessary data migration occurs
Solution Approach 1:
The patent segments the RAID storage space into multiple extents, where each extent can be independently managed and mapped to different disks. This allows flexible allocation of extents to disks based on actual needs rather than rigid even distribution, resolving the contradiction between uniformity and flexibility.
Solution Approach 2:
The patent implements dynamic extent mapping where the mapping between extents and disks can be adjusted based on system conditions. The extent allocation is not fixed but can be reallocated dynamically, enabling both uniform data distribution when needed and flexible management when requirements change.
2Ease of manufacture
If RAID creation pre-allocates extents across all stripes, then storage structure is established, but operation time is delayed due to extensive reallocation processes
Solution Approach 1:
The patent performs preliminary extent allocation only when necessary (e.g., when creating new stripes or expanding capacity) rather than pre-allocating for all stripes upfront. This selective preliminary action reduces the time loss during RAID creation while still establishing the necessary storage structure.
Solution Approach 2:
The system implements lazy extent allocation where extents are allocated on-demand based on actual write operations. The RAID structure serves itself by allocating extents only when needed, avoiding unnecessary reallocation processes and reducing creation time.
3Adaptability or versatility
If extents are reallocated during RAID maintenance, then storage optimization is achieved, but productivity is reduced due to data migration overhead
Solution Approach 1:
The patent extracts only the necessary extents for reallocation based on actual storage needs rather than migrating all data during maintenance. By taking out only the required portions for optimization, the data migration overhead is significantly reduced while still achieving storage optimization goals.
Solution Approach 2:
The patent applies partial reallocation actions during maintenance, performing extent reallocation only for specific stripes or regions that need optimization rather than comprehensive reallocation. This partial action reduces productivity loss while still achieving necessary storage optimization.
Data Source
AI summary
Embodiments of the present disclosure provide a method, apparatus and computer readable medium for managing a plurality of disks. The method includes in response to receiving a write request for a first stripe of a redundant array of independent disks (RAID), searching for extents mapped to the first stripe. The RAID is created on a plurality of extents obtained by dividing a plurality of disks. The method further includes, in response to the extents mapped to the first stripe being missed, selecting a first set of extents in a free state from the plurality of extents of the plurality of disks. The method further includes mapping the first stripe to the first set of extents.