Storage Control Apparatus Asynchronous UNMAP Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing method of responding to UNMAP commands in storage systems, which involves releasing physical storage areas and executing 0-write processing simultaneously, leads to prolonged response times and deteriorated performance due to the asynchronous nature of 0-write processing, causing cache memory shortages and delayed write-back operations.
Innovation Solution
A storage control apparatus that receives a UNMAP request, releases unit storage areas and responds asynchronously, while executing 0-write processing at a later time, allowing for immediate allocation of unallocated areas for new write requests and prioritizing write-back operations to prevent cache memory overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 0-write processing is executed simultaneously with releasing physical storage areas, then data leakage is prevented, but response time is prolonged and performance deteriorates
Solution Approach 1:
The system performs preliminary allocation of physical storage areas to virtual storage areas before actual write operations. When a UNMAP command is received, the system has already prepared the storage areas in advance, allowing it to quickly respond to the release request while separately managing the 0-write processing in the background, thus preventing data leakage without blocking the response.
2Loss of time
If 0-write processing is executed asynchronously after releasing unit storage areas, then response time is improved, but cache memory shortage occurs and write-back operations are delayed
Solution Approach 1:
The system segments the storage management into distinct components: allocation management, 0-write processing, and write-back operations. By separating these functions, the system can respond quickly to UNMAP commands while independently managing cache memory and write-back operations, preventing cache overflow and maintaining write-back productivity without being blocked by asynchronous 0-write processing.
3Productivity
If unit storage areas are allocated for new write requests immediately after release, then storage utilization is improved, but risk of allocating to areas needing 0-write increases
Solution Approach 1:
The system implements a feedback mechanism that tracks the status of physical storage areas through a bitmap structure. When a UNMAP command is received, the system sets corresponding bitmap bits to indicate that 0-write processing is needed. Before allocating released storage areas to new virtual volumes, the system checks the bitmap to ensure data security, while still maintaining high storage utilization by quickly making areas available for allocation.
Data Source
AI summary
A storage control apparatus comprising: a memory; and a processor coupled to the memory and configured to: receive a release request for a first storage area in a virtual storage area, release, among unit storage areas included in a physical storage area, one or more first unit storage areas allocated to the first storage area from the first storage area, execute overwrite processing of writing 0 to each of the first unit storage areas at a timing asynchronous with the release of the first unit storage areas, and when a write request is received to write data to the virtual storage area, execute write processing in which an unallocated unit storage area among the unit storage areas included in the physical storage area is allocated to a write destination area for the write data in the virtual storage area.