Storage Processor Copying via Physical Mapping
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Solution Overview
Problem
Existing data storage systems face inefficiencies in copying data between logical devices owned by different storage processors within the same data storage system, as they often require costly inter-processor communication and resource-intensive data transfer, especially when source and destination devices are owned by different processors.
Innovation Solution
A method and system for copying data that involves receiving a copy request, obtaining physical storage mapping information, locking logical addresses for exclusive access, storing data in a cache, and destaging it to the destination physical device location, while optimizing by transferring only mapping information rather than actual data between storage processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is copied between logical devices owned by different storage processors using traditional methods, then the copy operation can be completed, but inter-processor communication overhead and resource consumption increase significantly
Solution Approach 1:
The patent introduces mapping information as an intermediary that enables storage processor 1 to locate data on storage processor 2 without direct data transfer between processors. The mapping information acts as a mediator that contains the physical location data, allowing SP1 to read data locally and copy it without involving SP2 in the actual data transfer, thus reducing inter-processor communication overhead
Solution Approach 2:
The patent extracts the location information from the physical storage devices and consolidates it into separate mapping information structures. By taking out the mapping data from the data itself, the system allows storage processors to query location information without accessing the actual data, enabling efficient data location and copying without unnecessary processor involvement
2Productivity
If data is copied between logical devices owned by different storage processors, then the copy operation can be completed, but data transfer time increases due to inter-processor communication
Solution Approach 1:
The system performs preliminary action by pre-establishing and maintaining mapping information that contains physical location data before copy operations are needed. When a copy operation is initiated, the mapping information is already available, eliminating the need for real-time inter-processor queries and allowing immediate data location and copying, thus reducing processing time
Solution Approach 2:
Mapping information serves as an intermediary that provides direct access to physical location data without requiring inter-processor communication during the copy operation. This mediator layer allows storage processor 1 to independently determine where data is physically located and copy it efficiently without time-consuming coordination with storage processor 2
3Use of energy by moving object
If mapping information is transferred between storage processors instead of actual data, then resource consumption is reduced, but the system must maintain and manage additional mapping data structures
Solution Approach 1:
The mapping information structures serve multiple functions: they track physical data locations, enable copy operations, and provide a framework for managing data across multiple storage processors. By making the mapping system multi-functional, the patent reduces the need for separate mechanisms for each function, thereby managing complexity while providing comprehensive data management capabilities
4Reliability
If exclusive locks are acquired on logical addresses during copy operations, then data consistency is maintained, but access to the locked addresses is blocked during the operation
Solution Approach 1:
The patent applies locking locally to only the specific logical addresses that are the source or destination of the copy operation, rather than locking entire devices or volumes. This localized locking approach maintains data consistency for the specific data being copied while allowing other portions of the storage system to remain accessible, thus balancing reliability with operational ease
Data Source
AI summary
Techniques are described for copying data. At a first storage processor, a copy request is received to copy data including copying source data from a source area of a source logical device to a destination area of a destination logical device. The source logical device is owned by the first storage processor and the destination logical device is owned by a second storage processor. The first storage processor receives, from the second storage processor, destination location physical storage mapping information for the destination area. A destination physical device location corresponding to the destination area is determined. The source data from the source area is stored in a first cache location of a first data cache of the first storage processor. The first cache location is modified to indicate it includes write pending data for the destination physical device location. The source data is destaged to the destination physical device location.