Thin Provisioning Storage Capacity Verification
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Solution Overview
Problem
Thinly provisioned storage systems face the risk of data loss due to insufficient actual physical storage capacity, leading to failed write operations and a poor user experience, as allocation operations may succeed despite the lack of available physical storage.
Innovation Solution
The system detects available actual physical storage capacity before data allocation by maintaining an allocation map for virtual storage locations and a thin provisioning map for physical storage locations, ensuring that storage allocation fails early in the process if physical capacity is insufficient, thereby reducing data loss and improving user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thin provisioning is used to provide more storage capacity than physically available, then storage utilization is improved, but data loss risk increases due to failed write operations
Solution Approach 1:
The system performs preliminary verification of physical storage availability before allocating virtual storage space. When a write operation is initiated, the system first checks whether sufficient physical storage capacity exists, and only then proceeds with the allocation and write operations. This preliminary action prevents the fundamental contradiction by ensuring that virtual storage promises are backed by actual physical capacity before commitments are made.
Solution Approach 2:
The patent introduces an intermediary verification layer between the virtual storage allocation request and the physical storage write operation. This intermediary mechanism checks physical storage availability and either permits or blocks the operation accordingly, mediating between the thin provisioning virtualization layer and the physical storage layer to prevent data loss while maintaining storage efficiency.
2Speed
If storage allocation is performed without verifying physical capacity, then allocation speed is improved, but user experience deteriorates due to failed write operations
Solution Approach 1:
The system performs the capacity verification check as a preliminary action immediately when allocation is requested, rather than waiting until the write operation fails. This preliminary check adds minimal overhead while preventing subsequent failures, thereby maintaining fast allocation speeds while dramatically improving user experience by eliminating confusing allocation-write failures.
3Adaptability or versatility
If physical storage is added dynamically as usage increases, then storage flexibility is improved, but system complexity increases due to capacity monitoring requirements
Solution Approach 1:
The system implements self-service capacity monitoring where the storage management infrastructure automatically tracks physical storage availability and makes this information available to the allocation verification process. This self-service approach to capacity monitoring reduces operational complexity by eliminating the need for manual capacity tracking while maintaining dynamic storage flexibility.
Data Source
AI summary
A thinly provisioned storage system detects whether physical storage capacity is available when there is a request to allocate storage capacity, prior to data being written to the storage system. In particular, at the time when the file system allocates storage, such as when creating a file or performing an extending write (append) operation, allocating storage to an unallocated region of a sparse file, defragmenting a file, and the like, a storage system can verify that actual physical storage capacity is available. Thus, if there is insufficient actual physical capacity at the time when a storage allocation is attempted, then an error message can be sent and remedial action can be taken.