Host to Host Transfer of Sequential Media Using Persistent Reservations

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Solution Overview

Problem

Conventional sequential media network data storage devices face significant time delays and susceptibility to data loss due to the need for physical loading and unloading of magnetic media during host to host transfers, leading to underutilization and vulnerability during reservation transitions.

Innovation Solution

Implementing a method for host to host transfer of sequential media using persistent reservations, where logical unload and load commands are sent to hosts without physical media movement, and generating keys for persistent reservations to ensure seamless transfer and error recovery, utilizing SCSI persistent reservations for magnetic media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If physical loading and unloading of magnetic media is performed during host to host transfers, then data loss is prevented through exclusive reservation, but time delays increase significantly

Engineering Contradiction:

Improvedata loss preventionVSAvoidaccess time delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical system of physical media loading and unloading with a logical reservation system. Instead of physically moving magnetic tapes between hosts, the system uses persistent reservations to transfer control of the media logically, eliminating the time-consuming mechanical operations while maintaining data protection through the reservation mechanism.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a logical copy of the reservation state rather than physically moving the media. The persistent reservation mechanism copies the exclusive access rights from one host to another without requiring the physical media to be unloaded and reloaded, thus preventing data loss while eliminating access delays.

Inventive Principle:

Principle #26Copying

2Reliability

If physical unloading and reloading of media is performed during host to host transfer, then exclusive reservation is maintained, but media utilization efficiency decreases

Engineering Contradiction:

Improveexclusive reservationVSAvoidmedia utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the mechanical loading/unloading process with a logical persistent reservation system that maintains exclusive access rights without physical media movement. This allows the media to remain in the drive continuously, being logically transferred between hosts through reservation updates, thereby improving utilization efficiency while maintaining exclusive reservation protection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The persistent reservation mechanism enables continuous useful action by keeping the media in the drive without interruption. Instead of stopping the system to physically unload and reload media, the reservation is continuously updated between hosts, allowing the drive to remain productive throughout the transfer process.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If conventional reservation mechanism requires loading and unloading of magnetic tape for host transfer, then data loss is mitigated during transfer, but access time delay is perpetuated

Engineering Contradiction:

Improvedata loss mitigationVSAvoidaccess time delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent substitutes the conventional mechanical reservation mechanism that requires physical loading and unloading with a persistent reservation system that operates logically. The persistent reservation maintains data loss mitigation through exclusive access control while eliminating the time delays associated with mechanical media handling operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If physical media handling is performed during host to host transfer, then drive access control is maintained, but underutilization of magnetic media occurs

Engineering Contradiction:

Improvedrive access controlVSAvoidmedia utilization efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces physical media handling with persistent logical reservations that maintain drive access control without requiring media to be physically moved. This allows the media to remain continuously utilized in the drive while access control is maintained through the persistent reservation mechanism, eliminating underutilization.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8060642B2Techniques for host to host transfer of sequential media and use of persistent reservation to protect media during host to host transfer

Publication Date: 2011.11.15 COHESITY INC

AI summary

Techniques for host to host transfer of media and the use of persistent reservation to protect media during host to host transfer is disclosed. Exemplary embodiments may be realized as methods and systems for transferring a sequential media loaded in a drive from a first host to a second host without physically unloading the media. The first host may have a persistent reservation or non-persistent reservation of the drive. Likewise, the second host may have a persistent reservation or non-persistent reservation of the drive. Logical unload, logical load and preemption commands are utilized as is error recovery from a failed reservation.