GLOMAR Adaptive Consistency Control for Distributed File Systems Issues Current Distributed File Systems (DFS) are implemented on a mix of hardware platforms, software implementations and user requirements. Consistency maintenance techniques within DFS are usually scoped to a single scenario only (for example, mobility). However, being tightly scoped, reduces their ability to adapt when the conditions for which they were designed change. This being the case within a heterogeneous DFS. Simon Cuce

Solution Abstract consistency control out of the application and operating system Provide a generic construct to encapsulate consistency control functionality, via a component-oriented architecture (The Relationship Component) Allow developers to create specific implementations which can co-exist within a single DFS (Middleware) Implement a plugin architecture GLOMAR Middleware A middleware to house the different RCs. Provides a number of consistency control specific services Be able to define context specific heuristics (can be user defined) The ability to utilize RCs when appropriate, using these heuristics as the basis for decision making

Local Disk Application Filter Executive Network RC Manager RC Implemented RC Clone Manager ROI System Grader GLOMAR Responsible for Implementing RCs Determines heuristics Responsible for Remote File Operation Calls Responsible for Clone Management Responsible for RC Management Intercepting IO Operations GLOMAR Middleware Contains Consistency Control Functionality

Relationship Components Relationship Scope –Define context of RC –Context based on heuristics Clone List –Defines files this RC governs Consistency Model –Contains the Consistency Control implementation –Based on File System primitives (read, write, open, etc) –Divided into a Local and Remote interface Clone List Relationship Scope Consistency Model Relationship Component GLOMAR Implementation. NET (C#, VB.NET, MC++) Cross language support (for legacy approaches) Strong component support Support for emerging technologies (SOAP, WSDL, etc) A generic RC for operations in a mobile environment A full scale implementation of the Twin Transaction approach for concurrency control (A. Rasheed, Monash, 1999) A MS Outlook 2002 RC, implementing different consistency control techniques for each folder