BROADCAST Issues in Logging Techniques through a Study of Four Systems

BROADCAST will develop the principles for understanding, designing, and implementing large scale distributed computing systems (LSDCS), in three broad areas: Fundamental concepts. Evaluate and design computational paradigms (such as ordering, causality, consensus); structuring models (groups and fragmented objects); and algorithms (especially for consistency). Systems Architecture. Develop the architecture of LSDCS, in the areas of: naming, identification, binding and locating objects in LSDCS; resource management (e.g. garbage collection); communication and group management. Solutions should scale and take into account fragmentation, and recent technological developments (disconnectable devices and 64-bit address spaces). Systems Engineering. Efficiently supporting the architecture, exploiting the concepts and algorithms developed earlier, as kernel and storage support for numerous fine-grain complex objects; and programming support tools for building distributed applications. Broadcast Technical Reports can be ordered in hardcopy from the Broadcast Secretariat. They are also available electronically: by anonymous FTP from server broadcast.esprit.ec.org in directory projects/broadcast/reports; or through the CaberNet Infrastructure AFS filesystem, in directory /afs/research.ec.org/pro-jects/broadcast/reports. Logging is a particular storage semantic involving specific storage mechanisms, e.g. finding the log end or sequencing through a log. This paper presents the main logging techniques issues through a study of four existing logging systems implemented as independent storage systems: Clio, Camelot DLF, KI T L O G and Sprite LFS. It aims to provide a clear view of problems and actual solutions.