Storage Controller Metadata Conversion During Update
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Solution Overview
Problem
Existing storage systems experience performance degradation due to the overhead of determining and switching access destination metadata during controller updates, even when the update work is not performed.
Innovation Solution
A storage system with a controller that includes processors and memories configured to execute metadata conversion and control switching, using access control codes to manage metadata access between the original and new metadata formats during controller updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the process of determining and switching access destination metadata is added to each metadata access location in the control software, then the controller update work can be performed without stopping host access, but performance degradation occurs due to overhead even when controller update is not performed
Solution Approach 1:
The system dynamically switches between two operational modes: normal mode (using original metadata format) and update mode (using converted metadata format). The control software includes conditional logic that determines which mode is active and selectively executes appropriate access control codes, allowing the system to adapt its behavior based on whether controller update is being performed.
Solution Approach 2:
The control software is segmented into two distinct code paths: access control codes for the original metadata format and access control codes for the converted metadata format. This segmentation allows the system to use only the necessary code path depending on the operational state, avoiding the overhead of unnecessary determination and switching processes during normal operation.
2Reliability
If both metadata before conversion and new metadata after conversion are present in memory during the conversion period, then continuous host access can be maintained, but memory usage increases and complexity of metadata management increases
Solution Approach 1:
The system introduces an intermediary mechanism (access control codes with determination logic) that mediates between the dual metadata formats present in memory. This intermediary determines which metadata format should be accessed based on the current operational state, managing the complexity of having both formats coexist while maintaining continuous host access.
Solution Approach 2:
The control software is designed with universal access control codes that can handle both original and converted metadata formats. The determination process selects the appropriate format based on operational state, allowing a single software system to perform multiple functions (normal operation and update operation) without requiring separate code paths for each scenario.
3Manufacturing precision
If determination and switching processes are performed at each access location regardless of update state, then metadata access can be correctly managed during updates, but overhead occurs even during normal operation
Solution Approach 1:
The system implements dynamic code execution where the determination and switching processes are only activated when needed. A control flag or state indicator determines whether the system is in update mode or normal mode, allowing the software to skip unnecessary determination and switching operations during normal operation, thus reducing overhead while maintaining accuracy during updates.
Solution Approach 2:
The determination and switching logic is extracted as a separate, conditional process rather than being permanently embedded in every metadata access location. This extraction allows the system to remove or bypass these processes during normal operation, reducing overhead, while still providing accurate metadata access management when controller update is being performed.
Data Source
AI summary
Performance deterioration of a storage system is prevented. A storage controller includes one or more processors, and one or more memories configured to store one or more programs to be executed by the one or more processors. The one or more processors are configured to execute conversion of converting metadata before conversion for controlling the storage system into metadata after conversion in a format corresponding to a new controller newly installed in the storage system, execute control of switching an access destination between the metadata before conversion and the metadata after conversion according to an access control code during the conversion, and access the metadata before conversion without using the access control code before start of the conversion.