NFS File Handle Resolution via Centralized Controller

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Solution Overview

Problem

In network file systems (NFS), virtual machine migration often results in service interruptions due to the inability of new NFS servers to identify old file handles, requiring time-consuming connection disconnection and re-establishment processes, which do not meet the requirements for perception-free migration.

Innovation Solution

A method and device where an NFS server sends a parsing request for unidentifiable file handles to a centralized controller, which determines and returns a corresponding file identifier, allowing the NFS server to process I/O requests without interruption by maintaining mapping relationships between file handles and identifiers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the virtual machine uses the old NFS file handle after migration, then the I/O request processing can continue without interruption, but the new NFS server cannot identify the old file handle

Engineering Contradiction:

Improveservice continuityVSAvoidfile handle compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces a centralized controller as an intermediary component that maintains a global mapping between old NFS file handles and new file identifiers. When the new NFS server receives an I/O request with an unidentifiable old file handle, it queries the centralized controller, which resolves the mapping and returns the corresponding new file identifier, enabling the new server to process the request without service interruption

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The centralized controller serves multiple functions: it acts as a naming authority that maintains global file handle mappings, provides resolution services for unidentifiable file handles, and enables cross-NFS-server file access. This universal component allows the system to handle file handle compatibility across different NFS servers while maintaining service continuity

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the virtual machine disconnects and re-establishes the NFS connection during migration, then the new NFS server can identify the file, but the process is time-consuming and causes service interruption

Engineering Contradiction:

Improvefile handle identificationVSAvoidconnection re-establishment time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by pre-establishing the mapping relationship between old NFS file handles and new file identifiers in the centralized controller before migration occurs. During migration, the new NFS server can directly query this pre-prepared mapping information, eliminating the need for time-consuming connection disconnection and re-establishment processes

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical process of physically disconnecting and re-establishing NFS connections with a logical substitution approach. Instead of breaking the connection, the system uses a logical mapping mechanism through the centralized controller that allows the new NFS server to understand and process requests with old file handles, substituting the physical reconnection process with a logical mapping query

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If each NFS server maintains its own file handle mapping, then the NFS server can efficiently process local requests, but the file handle is not global and cannot be identified by other NFS servers

Engineering Contradiction:

Improverequest processing efficiencyVSAvoidfile handle global scope

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent merges the distributed file handle mapping information from multiple NFS servers into a centralized mapping maintained by the centralized controller. Each NFS server continues to maintain its local mapping for efficient local request processing, while the centralized controller maintains a global mapping that enables cross-server file handle resolution, combining both local efficiency and global accessibility

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10338849B2Method and device for processing I/O request in network file system

Publication Date: 2019.07.02 HUAWEI TECH CO LTD

AI summary

A method and device for processing an input/output (I/O) request in a network file system (NFS) includes sending, by a NFS server, a request for parsing the unidentifiable NFS FH to a centralized controller when a NFS file handle (NFS FH) in an I/O request cannot be identified, receiving, by the NFS server, a file identifier that corresponds to the unidentifiable NFS FH from the centralized controller according to the parsing request, where the file identifier is determined according to a pre-stored correspondence between NFS FHs and file identifiers, and processing, by the NFS server, the I/O request according to the file identifier.