Test LUN Performance Evaluation for Storage Migration
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Solution Overview
Problem
Conventional storage virtualization devices often fail to achieve expected improvements in response time after migrating a logical unit of storage (LUN) due to inadequate performance evaluation, leading to potential worsening of response times due to additional loading on the target array.
Innovation Solution
A method involving a storage performance test where a test LUN is added to a target array to mimic a production LUN, with host I/O requests duplicated to assess the target array's performance under real-time loading conditions, allowing for cancellation or continuation of migration based on predefined response time criteria, ensuring service level agreement compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a LUN is migrated from a first array to a second array based on existing performance indicators, then response time improvement is expected, but additional loading on the target array may prevent the expected improvement or even worsen response time
Solution Approach 1:
The system performs preliminary performance testing by adding a test LUN to the target array before actual migration. This test LUN mimics the production LUN and allows assessment of performance under realistic loading conditions. The testing phase includes duplicating host I/O requests to evaluate whether the target array can handle the additional load while maintaining expected response time improvements, thereby preventing premature migration decisions
Solution Approach 2:
The system creates a test LUN that copies the characteristics and workload of the production LUN. By duplicating host I/O requests and processing them on both the production LUN and test LUN simultaneously, the system can compare performance metrics without interrupting production work. This copying approach allows accurate prediction of migration outcomes by evaluating the target array's performance under conditions that mirror actual production scenarios
2Measurement precision
If performance testing is performed by duplicating host I/O requests on both production and test LUNs, then accurate performance assessment is achieved, but system complexity increases
Solution Approach 1:
The system introduces a test LUN as an intermediary between the host computers and the target array. This test LUN serves as a mediator that allows performance evaluation without directly impacting production systems. By routing a copy of host I/O requests through the test LUN, the system can measure performance metrics on the target array while the production LUN continues to serve production workloads unchanged
Solution Approach 2:
The system segments the I/O request processing into two parallel paths: one path processes requests on the production LUN while the other path processes duplicate requests on the test LUN. This segmentation allows independent performance measurement on the test LUN without interfering with production operations. The virtualization device maintains separate tracking and evaluation mechanisms for each path, enabling precise performance assessment while managing complexity through modular processing
Data Source
AI summary
A technique evaluates moving a logical unit of storage (LUN). The technique involves adding, while a host accesses a production LUN on a source array, a test LUN on a target array. The technique further involves duplicating host input/output (I/O) requests from the host to form a first set of the host I/O requests for processing on the production LUN on the source array and a second set of the host I/O requests for processing simultaneously on the test LUN on the target array. The technique further involves performing, while the first set of the host I/O requests are processed on the production LUN and the second set of the host I/O requests are processed simultaneously on the test LUN, a performance evaluation on the target array to assess a performance outcome of moving the production LUN from the source array to the target array.