Dynamic Mapped Logic Unit for RAID Storage Extent Allocation
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Solution Overview
Problem
Traditional RAID array LUN mapping is static and inefficient, leading to scalability issues and performance disruptions, especially in environments with layered applications and frequent data versioning and recovery needs, as it requires contiguous storage and lacks data segment sharing capabilities.
Innovation Solution
Dynamic mapping of LUN storage extents in a RAID environment using a mapped logic unit (MLU) that allocates storage extents on demand from a data storage extent pool, allowing for non-contiguous physical storage to be logically contiguous, enabling efficient allocation and sharing of storage resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If static mapping is used to provision LUNs to physically contiguous storage space, then simplicity and raw I/O performance are improved, but scalability and flexibility are limited
Solution Approach 1:
The patent implements dynamic mapping that allows LUNs to be mapped to non-contiguous physical storage segments that can be reallocated and remapped on-demand. This dynamic approach enables the storage system to adapt to changing requirements while maintaining performance, resolving the contradiction between static simplicity and scalability.
Solution Approach 2:
The patent divides the storage array into multiple segments that can be independently allocated and mapped to different LUNs. This segmentation allows flexible resource allocation where storage segments can be dynamically assigned based on demand, enabling both high performance and scalability simultaneously.
2Reliability
If LUNs are copied in their entirety using copy on first write for snapshots, then point-in-time copies are preserved, but significant performance disruption occurs due to read/write cycles
Solution Approach 1:
The patent implements copy-on-write technology where data blocks are copied to snapshot storage only when modified. This allows multiple snapshots to share the same physical blocks until changes occur, eliminating the performance disruption of traditional copy methods while preserving snapshot integrity through efficient block-level copying.
Solution Approach 2:
The patent uses a thin provisioning layer that creates virtual snapshots without physically duplicating data. This thin film approach allows snapshots to be created instantly with minimal performance impact, as the snapshot structure is lightweight and only actual data changes trigger physical copy operations.
3Ease of operation
If contiguous storage space is provisioned for each LUN, then storage management is simplified, but storage efficiency is reduced due to inability to share data segments
Solution Approach 1:
The patent merges multiple LUNs at the logical level while maintaining independent management interfaces. This allows different LUNs to share underlying physical storage segments, improving storage efficiency while preserving the simplicity of individual LUN management through virtualization that combines resources without complicating operations.
4Device complexity
If static LUN mapping is used, then data placement control is limited, but system complexity is reduced
Solution Approach 1:
The patent introduces a dynamic mapping layer that acts as an intermediary between LUNs and physical storage. This mediator handles the complexity of dynamic allocation and data placement control transparently, allowing sophisticated placement strategies without exposing complexity to users or applications.
Data Source
AI summary
Disclosed are methods, systems, and computer program products for dynamic mapping of logical unit (LUN) storage extents in a redundant array of inexpensive disks (RAID) environment. According to one method, a data storage extent pool representing at least a portion of a RAID array and including at least one data storage extent is provisioned. A first mapped logic unit (MLU) for allocating data storage extents from the data storage extent pool is created. A first data storage extent is allocated, using the first MLU, in response to a data write operation.