Hierarchical Storage Data Migration During Drive Idle Time

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Solution Overview

Problem

In hierarchical storage systems, the inefficiencies in reclamation and inter-generation copy processes lead to underutilization of drive resources due to prolonged reading times and waiting times, especially when copying data from old generation tape media to new generation media, where the write transfer rate of the new generation is not fully utilized.

Innovation Solution

A method that estimates the waiting time for data transfer and selects migration target data based on whether migration to the target medium is expected to be finished within this waiting time, allowing simultaneous reading and writing operations to optimize resource utilization by migrating data during spare times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If data is copied from source medium to target medium using conventional sequential reading, then data transfer is completed, but drive resources are underutilized due to prolonged waiting time

Engineering Contradiction:

Improvedrive resource utilizationVSAvoidwaiting time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by migrating additional data during the waiting time period. Specifically, while the source drive is locating and reading copy target data (creating waiting time), the system proactively migrates other data from the source medium to the target medium in advance, thereby utilizing otherwise idle drive resources and reducing overall completion time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system maintains continuous useful action by ensuring the target drive operates continuously without idle waiting time. By calculating the waiting time for copy target data and selecting migration target data that can be migrated within this period, the target drive continuously performs writing operations, eliminating idle time and maximizing productivity.

Inventive Principle:

Principle #20Continuity of useful action

2Productivity

If tape drives operate sequentially to locate data on source medium, then data can be read, but reading time is prolonged reducing overall efficiency

Engineering Contradiction:

Improvereading speedVSAvoidreading time

Core Design Contradiction:

ProductivityVSDuration of action of moving object

Solution Approach 1:

The system performs preliminary migration actions during the sequential reading process. While the source drive sequentially locates and reads copy target data (which inherently takes time), the system has already selected migration target data and prepared it for migration, overlapping the reading process with migration preparation to reduce total operation time.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If two drives are occupied during reclamation process, then data transfer occurs, but target drive waits for data from source drive reducing resource utilization

Engineering Contradiction:

Improvedrive utilizationVSAvoidwaiting time for data transfer

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary selection of migration target data based on the calculated waiting time. By identifying and preparing migration target data before the actual transfer begins, the target drive can immediately start writing operations as soon as data becomes available, eliminating idle waiting time and maximizing utilization of both drives.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the calculated waiting time to dynamically adjust migration target selection. The waiting time calculation provides feedback that informs which data should be prioritized for migration, allowing the system to optimize the use of both drives based on real-time conditions and maximize overall throughput.

Inventive Principle:

Principle #23Feedback

4Productivity

If speed matching capability adapts write transfer rate to read transfer rate, then data transfer is possible, but new generation medium does not utilize its full write capability

Engineering Contradiction:

Improvewrite transfer rateVSAvoidspeed matching

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary actions by selecting multiple migration target data items that can be migrated within the waiting time period. This allows the target drive to maintain higher write speeds by having a pipeline of data ready to write, rather than waiting sequentially for each data item, thereby better utilizing the new generation medium's write capability while maintaining adaptability through intelligent selection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11314439B2Copy from source medium to target medium

Publication Date: 2022.04.26 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A computer-implemented method, according to one embodiment, includes: estimating, by the computer system, a waiting time for copy target data to be transferred from the source medium. The waiting time includes an estimated time for locating and reading the copy target data from the source medium. The method also includes selecting, by the computer system, migration target data on the source medium based on whether migration of data to the target medium is expected to be finished within the waiting time. The selecting is based at least in part on comparing a size of the data and an allowable size calculated based on the waiting time and an estimated write transfer rate to the target medium. The method further includes migrating, by the computer system, the migration target data from the source medium to the target medium.