Storage Cache Log Invalidation Using Sequence Numbers

Solution Overview

Problem

Existing storage systems face performance bottlenecks due to costly search operations for invalidation of logs during asynchronous destage, which is inefficient and time-consuming.

Innovation Solution

Implement a storage system with a nonvolatile storage device and a processor that uses a cache data log area for storing cache data logs, creating log headers with sequence numbers, registering these in an invalidation table, and performing high-speed invalidation by deleting logs older than the registered sequence numbers during garbage collection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a search is performed to determine whether a log can be invalidated for each log during asynchronous destage, then log invalidation accuracy is improved, but processing time and system performance deteriorate

Engineering Contradiction:

Improvelog invalidation accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-registering sequence numbers in an invalidation table before garbage collection occurs. When data is written to cache or destaged to permanent storage, the corresponding log sequence numbers are registered in advance in the invalidation table. This allows the garbage collection process to simply compare sequence numbers without performing costly search operations, thereby resolving the contradiction between accurate log invalidation and processing time efficiency

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If a search is performed to determine whether a log can be invalidated for each log during asynchronous destage, then log invalidation accuracy is improved, but system performance deteriorates

Engineering Contradiction:

Improvelog invalidation accuracyVSAvoidsystem performance

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-registering sequence numbers in an invalidation table before garbage collection occurs. When data is written to cache or destaged to permanent storage, the corresponding log sequence numbers are registered in advance in the invalidation table. This allows the garbage collection process to simply compare sequence numbers without performing costly search operations, thereby resolving the contradiction between accurate log invalidation and processing time efficiency

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20250328473A1Storage system and storage control method

Publication Date: 2025.10.23 HITACHI VANTARA LTD

AI summary

A nonvolatile storage device has a permanent area and a cache data log area. A memory has a cache data area. A processor stores data related to a write request in the cache data area, stores a log header having a sequence number and data stored in the memory in a cache data log area, responds to a write request source, registers a sequence number of the log header in an invalidation table, destages the data stored in the memory to the permanent area, creates a log header having a sequence number, registers the sequence number in the invalidation table, and when the cache data log area is collected by a garbage collection method, deletes a log header having a sequence number older than the sequence number registered in the invalidation table and corresponding data from the cache data log area to release the storage area.