File Server Namespace Consistency via Operation Segmentation
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Solution Overview
Problem
In distributed file systems where multiple NAS apparatuses access a single CAS apparatus, namespace consistency issues arise due to collisions when file paths created by different NAS apparatuses collide, leading to reduced usability as only one NAS apparatus can perform file operations while others are locked out, and moving collided objects to a 'conflict' directory complicates the namespace and user access.
Innovation Solution
A file server apparatus that mediates access between clients and a shared file system volume, using a controller to differentiate between directory and file operations, synchronously transmitting directory operations and asynchronously transmitting file operations to the CAS apparatus, allowing for immediate response to clients while ensuring namespace consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lock function is used to guarantee namespace consistency, then consistency is improved, but file operation speed deteriorates because only one NAS apparatus can execute file operations at a time
Solution Approach 1:
The patent segments file operations into two categories: directory operations and file operations. Directory operations are transmitted synchronously to the CAS apparatus to maintain namespace consistency, while file operations are transmitted asynchronously to improve processing speed. This segmentation allows different operation types to be handled with different transmission modes, resolving the contradiction between consistency and speed.
Solution Approach 2:
The patent dynamically adjusts the transmission mode based on the operation type. For directory operations that affect namespace structure, synchronous transmission is used to ensure immediate consistency. For file operations that do not affect namespace, asynchronous transmission is used to improve speed. This dynamic approach allows the system to adapt its consistency mechanism to the specific operation being performed.
2Reliability
If collided objects are moved to a 'conflict' directory to solve namespace consistency, then consistency is improved, but usability deteriorates due to namespace complexity and user access difficulty
Solution Approach 1:
The patent extracts the namespace consistency validation logic from the file operation process itself and places it in the directory operation transmission phase. By validating and resolving potential collisions during directory operations (which are transmitted synchronously), the system prevents collided objects from being created in the first place, eliminating the need for a 'conflict' directory and maintaining a clean, simple namespace structure.
Solution Approach 2:
The patent performs preliminary validation of file paths during directory operations before actual file operations occur. By checking for potential namespace collisions in advance and resolving them during the synchronous directory operation transmission, the system prevents collision-related usability issues before they arise, maintaining both consistency and usability.
3Productivity
If multiple NAS apparatuses transmit cached objects simultaneously, then file operation speed is improved, but namespace consistency deteriorates due to object collisions
Solution Approach 1:
The patent applies different transmission quality levels to different operation types. Directory operations, which have local impact on namespace structure, are transmitted with high quality (synchronously) to ensure immediate consistency. File operations, which have less impact on namespace, are transmitted with lower quality requirements (asynchronously) to improve speed. This local quality differentiation resolves the contradiction between speed and consistency.
Data Source
AI summary
A file server apparatus includes a second file system volume including cache data of a first file system volume stored in a shared file storage apparatus. The file server apparatus determines the operation type indicated by an access request to the first file system volume from a client. When the operation type is directory operation, the file server sends an instruction of directory operation to the shared file storage apparatus, and then transmits a completion response to the client. When the operation type is file operation, the file server apparatus executes a file operation in the second file system volume, transmits a completion response to the client, and then transmits a file operation instruction to the shared file storage apparatus.