Data granularity: The data within a P2P system can be accessible at many degrees of granularity. At the atomic granularity level, data consists of a collection of indivisible objects, ., complete MP3 files. For data placement at this level, we have to either place an entire object at a peer, or not at all; this is the semantics currently supported by today’s P2P systems. At the hierarchical granularity level, sets of objects can be grouped into larger objects, thus forming hierarchies. For example, multiple MP3 files may be grouped into an album, and albums into collections; for the data placement problem at this level, we.
