zFS – A Scalable Distributed File System Using Object

zFS is a research project aimed at building a decentral-ized file system that distributes all aspects of file and stor-age management over a set of cooperating machines inter-connected by a high-speed network. zFS is designed to be a file system that scales from a few networked computers to several thousand machines and to be built from commodity off-the-shelf components. The two most prominent features of zFS are its coop-erative cache and distributed transactions. zFS integrates the memory of all participating machines into one coher-ent cache. Thus, instead of going to the disk for a block of data already in one of the machine memories, zFS re-trieves the data block from the remote machine. zFS also uses distributed transactions and leases, instead of group-communication and clustering software. This article describes the zFS high-level architecture and how its goals are achieved. 1