DOC-a file system cache to support mobile computers

Abstract

This paper identifies design requirements of system-level support for mobile computing in small form-factor battery-powered portable computers and describes their implementation in DOC (Disconnected Operation Cache). DOC is a three-level client caching system designed and implemented to allow mobile clients to transition between connected, partially disconnected and fully disconnected modes of operation with minimal user involvement. Implemented for notebook computers, DOC addresses not only typical issues of mobile elements such as resource scarcity and fluctuations in service quality but also deals with the pitfalls of MS-DOS, the operating system which prevails in the commercial notebook market. Our experiments performed in the software engineering environment of AST Research indicate not only considerable performance gains for connected and partially disconnected modes of DOC, but also the successful operation of the disconnected mode.