Eecient S C Hemes for Broadcasting Popular Videos ?

We provide a formal framework for studying broadcasting schemes and design a family of schemes for broadcasting popular videos, called the Greedy Diskconserving Broadcasting (GDB) scheme. We analyze the resource requirements for GDB, i.e., the number of server broadcast channels, the client storage space, and the client I/O bandwidth required by GDB. The analysis shows that GDB exhibits a tradeo between any two of the three resources. We compare our scheme with a recently proposed broadcasting scheme, Skyscraper Broadcasting (SB). With GDB, we can reduce the client storage space by as much as 50% or the number of server channels by as much as 30% at the cost of a small additional increase in the amount of client I/O bandwidth. If we require the client I/O bandwidth of GDB to be identical to that of SB, GDB needs only 70% of the client storage space required by SB or one less server channel than SB does. In addition, we show that with small client I/O bandwidth, the resource requirements of GDB are close to the minimum achievable by any disk-conserving broadcasting scheme.