Storage Block Mapping Protocol for Distributed Metadata Management

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Solution Overview

Problem

Data consistency issues arise in distributed data processing systems when multiple file servers share access to the same file system, leading to challenges in managing metadata and ensuring data integrity across networked storage arrays.

Innovation Solution

A cached disk array system with a global cache memory, front-end directors, and disk directors that implement a storage block mapping protocol for virtual logical units, allowing for space allocation and mapping information to be managed by a storage allocation server, enabling efficient data access and metadata management across multiple storage arrays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple file servers share access to the same file system, then access flexibility and resource utilization are improved, but data consistency and metadata management become problematic

Engineering Contradiction:

Improveaccess flexibilityVSAvoiddata consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the file system into multiple independent volumes, each owned by a specific file server. This allows multiple file servers to access different volumes simultaneously without conflicting, while maintaining data consistency within each volume through dedicated ownership. The segmentation resolves the contradiction by enabling shared access flexibility at the system level while preserving data consistency at the volume level.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a volume manager as an intermediary layer between file servers and storage devices. The volume manager handles metadata management and access coordination, allowing file servers to access storage resources without direct conflicts. This intermediary manages the shared access while maintaining data consistency through centralized control of volume-level metadata.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If one file server is designated as exclusive owner of access rights, then data consistency is maintained, but access flexibility and resource utilization are reduced

Engineering Contradiction:

Improvedata consistencyVSAvoidaccess flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of having one exclusive owner for the entire file system, the patent segments ownership across multiple file servers, each owning specific volumes. This segmentation allows each file server to have exclusive control over its owned volumes (maintaining data consistency) while the system as a whole supports flexible access to multiple volumes by different servers (improving access flexibility).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The volume manager provides universal functionality that enables multiple file servers to perform metadata management operations on volumes they don't own. This multi-functionality allows file servers to access and manage storage resources beyond their own volumes, improving access flexibility while the ownership model maintains data consistency through dedicated responsibility for each volume.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If metadata management tasks are delegated to secondary file servers, then resource utilization is improved, but complexity of metadata management increases

Engineering Contradiction:

Improveresource utilizationVSAvoidmetadata management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments metadata management responsibilities by volume ownership. Each file server is primarily responsible for metadata management of its owned volumes, while secondary servers can assist with specific operations. This segmentation clarifies responsibilities and reduces overall system complexity compared to fully distributed metadata management, while still improving resource utilization through delegated operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The volume manager acts as an intermediary that coordinates metadata management operations between primary and secondary file servers. It receives requests from secondary servers, validates them against ownership rules, and executes appropriate operations. This intermediary layer simplifies the complexity by providing a standardized interface and control mechanism, while still enabling improved resource utilization through delegated metadata management tasks.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7653832B2Storage array virtualization using a storage block mapping protocol client and server

Publication Date: 2010.01.26 EMC IP HLDG CO LLC

AI summary

A cached disk array includes a disk storage array, a global cache memory, disk directors coupling the cache memory to the disk storage array, and front-end directors for linking host computers to the cache memory. The front-end directors service storage access requests from the host computers, and the disk directors stage requested data from the disk storage array to the cache memory and write new data to the disk storage. At least one of the front-end directors or disk directors is programmed for block resolution of virtual logical units of the disk storage, and for obtaining, from a storage allocation server, space allocation and mapping information for pre-allocated blocks of the disk storage, and for returning to the storage allocation server requests to commit the pre-allocated blocks of storage once data is first written to the pre-allocated blocks of storage.