Storage System Free Extent Allocation via Mapping Cache
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Solution Overview
Problem
Existing storage systems face challenges in rapidly expanding storage capacity and improving performance when additional storage devices are added, as users must wait for address mapping updates to complete before accessing newly expanded storage space.
Innovation Solution
A method and apparatus that identify free extents in multiple storage devices, map virtual address ranges to physical address ranges of these extents, and allocate storage space, allowing partial access before complete address mapping is finished.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If address mapping update is completed before allocating storage space to users, then data reliability is ensured, but user wait time increases and storage system performance deteriorates
Solution Approach 1:
The system performs preliminary identification of free extents in storage devices before the address mapping update is complete. By preparing the mapping information in advance and maintaining a mapping information cache, the system enables users to access storage space as soon as the preliminary mapping is ready, rather than waiting for the entire update process to finish. This preliminary action significantly reduces user wait time while maintaining data reliability through the cache validation mechanism.
Solution Approach 2:
The patent introduces a mapping information cache as an intermediary component between the address mapping update process and user access requests. This cache stores mapping information temporarily and allows users to access storage space through the cache while the background update continues. The intermediary cache decouples the update process from user access, enabling concurrent operations without compromising data reliability.
2Reliability
If address mapping update is completed before storage space allocation, then data consistency is maintained, but storage system productivity decreases
Solution Approach 1:
The system performs preliminary identification of free extents and prepares mapping information before the address mapping update completes. This allows storage space to be allocated to users based on preliminary mapping data, enabling parallel execution of space allocation and update processes. The preliminary action approach maintains data consistency through cache validation while significantly improving storage system productivity by eliminating sequential processing bottlenecks.
Solution Approach 2:
The patent enables continuous useful action by allowing storage space allocation and user access to proceed concurrently with the address mapping update in the background. The mapping information cache ensures that user access operations continue uninterrupted while the update process completes. This continuity principle transforms the traditional stop-and-wait approach into a parallel processing model, dramatically improving storage system productivity.
3Stability of the object's composition
If complete address mapping update is required before accessing expanded storage space, then storage system stability is ensured, but expansion speed deteriorates
Solution Approach 1:
The system implements partial action by allowing users to access storage space based on preliminary mapping information before the complete address mapping update is finished. The mapping information cache stores sufficient mapping data to enable partial access to expanded storage space. This partial action approach maintains storage system stability through cache validation while achieving rapid expansion speed by not requiring the entire update process to complete before user access.
Solution Approach 2:
By performing preliminary identification of free extents and preparing mapping information in advance, the system enables fast expansion access. The preliminary mapping information stored in the cache allows users to access expanded storage space immediately, achieving high expansion speed while maintaining stability through the cache mechanism that ensures data integrity during the ongoing update process.
Data Source
AI summary
A storage system is associated with at least one part of multiple storage devices in a resource pool, a part of a storage space in a storage device being inaccessible to the storage system. Techniques involve: identifying an extent within the part of the storage space in the storage device as a free extent; selecting a group of storage devices each with a free extent from the multiple storage devices in response to determining a virtual address range in the storage system as specified by an access request is inaccessible; mapping the virtual address range to a physical address range of the free extents in the group of storage devices; and allocating a storage space specified by the physical address range to the storage system. Therefore, the expansion of the resource pool can be implemented more conveniently and rapidly, and performance of the storage system can be improved.