Mirroring Cache List for Demoting Modified Tracks

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Solution Overview

Problem

Existing data backup systems face inefficiencies when demoting tracks from cache in mirror copy relationships, leading to increased latency due to premature removal from cache before transfer to secondary storage.

Innovation Solution

Implementing a mirroring cache list to selectively demote and transfer modified tracks from primary storage to secondary storage, ensuring tracks are transferred before demotion and utilizing separate demote cache lists for non-mirrored tracks to optimize cache management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If cache management algorithms select tracks to demote from cache to free space, then cache space is freed for further data, but tracks in mirror copy relationships may be demoted before being transferred to secondary storage resulting in increased latency

Engineering Contradiction:

Improvecache space availabilityVSAvoidlatency for mirroring tracks

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent segments the cache management process by creating a separate mirroring cache list that is processed independently from the main demotion algorithm. This segmentation allows tracks to be identified for mirroring before demotion decisions are made, ensuring that tracks needed for mirroring are not prematurely removed from cache. The mirroring cache list acts as a protected subset of cache tracks that are prioritized for transfer to secondary storage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary action by processing the mirroring cache list before executing demotion operations. Tracks are identified and marked for mirroring in advance, and this preliminary identification ensures that when demotion decisions are made, the system is aware of which tracks need to be transferred to secondary storage. This preliminary action prevents the latency problem by ensuring tracks are not demoted before their mirroring transfer can occur.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If tracks are transferred from cache to secondary storage, then data consistency is maintained, but cache space is consumed reducing availability for other data

Engineering Contradiction:

Improvedata consistencyVSAvoidcache space availability

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent implements dynamic cache management where the mirroring cache list is continuously updated and processed. Tracks are dynamically transferred from cache to secondary storage based on the mirroring requirements, and cache space is dynamically freed as transfers complete. This dynamic approach allows the system to maintain data consistency by ensuring tracks are transferred when needed, while simultaneously optimizing cache space availability through continuous adjustment of the cache contents based on current mirroring needs.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11321234B2Using a mirroring cache list to demote modified tracks from cache

Publication Date: 2022.05.03 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Provided are a computer program product, system, and method for using mirroring cache list to demote modified tracks from cache A modified track for a primary storage stored in the cache to mirror to a secondary storage is indicated in a mirroring cache list. The mirroring cache list is processed to select modified tracks in the cache to transfer to the secondary storage that have not yet been transferred. The selected modified tracks in the cache are transferred to the secondary storage. The mirroring cache list is processed to determine modified tracks in the cache to demote from the cache.