Conventional wisdom holds that reducing disk latency
leads to higher disk utilization, maximizing disk 
utilization leads to higher throughput, employing a 
faster disk leads to better performance.  All of this 
is true when building a conventional file or database system.
In this paper we show that these principles can be misleading 
when applied to a media server. We examine a number 
of techniques that have been developed for maximizing
disk bandwidth utilization in media servers, including disk 
arm scheduling and data placement ones. We show that, some disk
latency reduction techniques can be counterproductive 
since memory, rather than disk, is the bottleneck
in improving throughput.  We present techniques for best 
memory use under different disk policies, and derive precise 
formulas for computing memory use.  In addition, to precisely account
for the design tradeoffs between disk bandwidth and memory use,
we propose a cost-based approach that focuses on minimizing
the per-stream costs, including the disk and memory ones.  
Lastly, we study the 
worst-case initial latency of presentations, a factor 
that may be important in interactive systems.  We present 
a novel technique for significantly reducing this initial 
latency under some disk scheduling schemes.