Flash Package Controller Snapshot Management via Selective Area Allocation
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Solution Overview
Problem
Conventional storage systems using flash memory face inefficiencies in snapshot management, where entire logical storage areas are managed as snapshots even if only partial areas require it, leading to unnecessary data storage and a high load on a single controller.
Innovation Solution
The system employs multiple flash packages with package controllers to manage logical units differently, allocating separate physical storage areas for backup and non-backup data, allowing flexible snapshot management and distributing the load across controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire logical storage area is managed as a snapshot even when only partial areas require it, then snapshot coverage is improved, but storage space is wasted and controller load increases
Solution Approach 1:
The patent divides the logical storage area into multiple segments or regions, allowing different snapshot management policies to be applied to different segments. This enables selective snapshot acquisition for only those portions of the storage area that require it, rather than managing the entire logical storage area as a single snapshot unit, thus reducing unnecessary storage space consumption while maintaining adequate snapshot coverage for critical data regions.
Solution Approach 2:
The patent implements differential snapshot management where different quality levels of snapshot management are applied to different regions of the logical storage area. Critical regions receive full snapshot management for high reliability, while non-critical regions use reduced or no snapshot management, optimizing the balance between snapshot coverage and storage space utilization based on local requirements.
2Device complexity
If control for managing logical-physical storage area association, address conversion, RAID control, and snapshot management is centralized in a single controller, then system simplicity is improved, but controller load becomes excessive
Solution Approach 1:
The patent segments the control functions across multiple controllers in a distributed architecture. Different controllers are assigned specific responsibilities such as logical-physical storage area association management, address conversion, RAID control, and snapshot management. This distribution reduces the processing load on any single controller while maintaining comprehensive system functionality through coordinated operation of multiple specialized controllers.
3Reliability
If pre-update old data is stored in the system after update data is stored, then snapshot capability is improved, but unnecessary old data accumulates in storage areas that do not require management
Solution Approach 1:
The patent extracts only the necessary old data that is required for snapshot reconstruction, rather than retaining all pre-update old data. By identifying and isolating specifically those data portions that are needed for snapshot purposes, the system maintains snapshot capability while avoiding the accumulation of unnecessary old data in storage areas, thus improving storage efficiency.
Solution Approach 2:
The patent applies partial snapshot management by retaining only the minimal necessary old data required for snapshot functionality, rather than excessively retaining all possible old data. This partial action approach ensures snapshot capability is maintained for critical data while avoiding the storage overhead of retaining excessive old data that is not needed for snapshot reconstruction.
Data Source
AI summary
Package controller of a flash package, upon receiving an update data write request with respect to a first logical storage area corresponding to a first LU that is treated as a backup target, manages a first physical storage area as a backup storage area in a state where pre-update data is maintained, allocates a second physical storage area to the first logical storage area, and writes the update data to the second physical storage area. The package controller, upon receiving an update data write request with respect to a second logical storage area corresponding to a second LU that is treated as a non-backup target, manages a third physical storage area allocated to the second logical storage area as an invalid storage area, and writes the update data to a fourth physical storage area newly allocated to the second logical storage area.