FlashCopy Target Disk Cleaning Rate Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cascaded FlashCopy implementations face challenges in scalability and flexibility, particularly in managing dependencies between target disks, which complicates stopping or re-triggering FlashCopy mappings, leading to increased overheads and inaccessible target disks during cleaning processes.
Innovation Solution
A method and system that utilize a rate control component to set a desired cleaning rate, a comparator to identify discrepant bits in bitmaps, and a copy initiator to initiate copy operations from one target to another, allowing for efficient cleaning of dirty grains while maintaining system accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cascaded FlashCopy implementations are used to support multiple target disks, then the number of supported targets increases, but the complexity of managing dependencies between targets increases and target disks become inaccessible during cleaning processes
Solution Approach 1:
The patent segments the cleaning process into independent per-target operations rather than requiring coordinated cascaded cleaning. Each target disk's cleaning is handled independently, eliminating the complex dependency management between targets while maintaining support for multiple targets.
Solution Approach 2:
The system performs preliminary identification of dirty grains using bitmaps before initiating copy operations. This preliminary action allows the system to plan and execute cleaning operations efficiently without requiring targets to be inaccessible, as the dependency relationships are resolved in advance.
2Reliability
If cleaning operations are performed on target disks in cascaded FlashCopy, then data consistency is maintained, but target disks become inaccessible during cleaning increasing downtime
Solution Approach 1:
The patent implements self-service cleaning where each target disk's cleaning operation is independently managed and can proceed without blocking other targets. The system automatically identifies dirty grains and performs copy operations in the background, maintaining data consistency while minimizing access interruptions through automated dependency resolution.
Solution Approach 2:
The system changes the operational parameters of cleaning by allowing it to proceed with controlled inaccessibility rather than complete blocking. By using bitmaps to track dirty grains and managing copy operations dynamically, the system reduces the duration and impact of target disk inaccessibility while maintaining consistency.
3Adaptability or versatility
If multiple targets are supported in cascaded FlashCopy, then backup and historical access capabilities are enhanced, but overhead of cleaning and dependency management increases
Solution Approach 1:
The patent uses bitmap-based tracking to identify dirty grains that need copying, enabling efficient selective copy operations rather than full target cleaning. This copying approach maintains versatility for multiple backup targets while reducing overhead by only copying necessary data blocks based on actual write operations.
Solution Approach 2:
The system efficiently manages multiple targets by discarding the complexity of cascaded dependency management and recovering through independent per-target cleaning operations. Bitmaps track which grains need cleaning, allowing the system to discard unnecessary dependency tracking while recovering only the essential cleaning functionality for each target independently.
Data Source
AI summary
A storage control apparatus in cooperation with a plurality of controlled storage apparatus arranged in a cascade of point-in-time copy relationship. The apparatus includes: a rate control component operable to set a desired rate for cleaning a first target one of the plurality of controlled storage apparatus; a comparator component in communication with the rate control component to identify discrepant bits associated with first and second targets; and a copy initiator, responsive to the comparator component to initiate a copy operation responsive to the identified discrepant bits.