Storage Reservation Handling Across SCSI and NVMe Protocols

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Solution Overview

Problem

Conventional techniques face challenges in seamlessly switching between different storage access protocols, such as SCSI and NVMe, while maintaining consistent reservation handling, which can lead to inefficiencies and performance degradation in storage systems.

Innovation Solution

Implementing a multi-path layer with an MPIO driver that registers logical storage devices for multiple access protocols using a common host identifier, translates reservation commands between protocols, and manages reservations independently of the access protocol used, allowing seamless switching between SCSI-FC and NVMeF, and vice versa.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional techniques are used to switch between SCSI and NVMe access protocols, then protocol transformation can be achieved, but reservation handling becomes inconsistent and problematic

Engineering Contradiction:

Improveprotocol switching capabilityVSAvoidreservation handling consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a protocol translation layer that acts as an intermediary between SCSI and NVMe protocols. This layer translates reservation commands from one protocol to another, ensuring consistent reservation handling while enabling protocol switching. The translation layer maintains reservation state information and coordinates between different protocol implementations, resolving the inconsistency problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements a universal reservation management mechanism that works across multiple access protocols (SCSI, NVMe, and others). By creating a protocol-agnostic reservation handling framework, the system enables consistent reservation semantics regardless of which access protocol is being used, thereby improving reliability during protocol transformations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If host devices are reconfigured to utilize a different access protocol, then protocol flexibility is improved, but system complexity and reconfiguration problems increase

Engineering Contradiction:

Improveaccess protocol flexibilityVSAvoidreconfiguration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The protocol translation layer serves as an intermediary that abstracts the complexity of protocol switching from host devices. Instead of requiring complex reconfiguration of host devices, the translation layer handles protocol conversions transparently, maintaining simple host device configurations while enabling protocol flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system segments the protocol handling functionality into distinct layers: a host device layer that issues protocol-agnostic commands, a translation layer that handles protocol-specific conversions, and a storage device layer that executes operations. This segmentation isolates complexity to the translation layer, allowing protocol flexibility without increasing overall system complexity.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If multiple host devices access a logical storage device using different access protocols, then system versatility is improved, but reservation coordination becomes problematic

Engineering Contradiction:

Improvemulti-protocol access capabilityVSAvoidreservation coordination

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The protocol translation layer acts as a central coordinator for reservations across multiple host devices using different protocols. It maintains a unified view of reservation state and translates reservation commands from various protocols into a common internal representation, ensuring proper coordination without requiring complex inter-host communication.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system merges reservation management functionality into a unified protocol translation layer that handles reservations for all access protocols. By combining reservation handling across SCSI, NVMe, and other protocols into a single coordination mechanism, the system simplifies reservation coordination while supporting multi-protocol access.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11455116B2Reservation handling in conjunction with switching between storage access protocols

Publication Date: 2022.09.27 EMC IP HLDG CO LLC

AI summary

At least one processing device is configured to register a logical storage device of a storage system for a first set of paths associated with a first access protocol using a host identifier, to send a first reservation command in the first access protocol over each of the paths in the first set of paths, to register the logical storage device of the storage system for a second set of paths associated with a second access protocol using the same host identifier used in registering the logical storage device for the first set of paths, to receive an additional reservation command in the first access protocol, and responsive to receipt of the additional reservation command in the first access protocol, to translate the additional reservation command to the second access protocol, and to send the additional reservation command in the second access protocol to the storage system.