A cache odyssey

This thesis describes the effect of write caching on overall file system performance. It will show through simulations that extensive write caching greatly reduces average file read latency. Extensive write caching reduces the number of disk writes and minimizes disk read/write contention. By taking a closer look at file system write semantics, it will also show that write optimized file systems are not the key issue for UNIX like file systems. Write optimized file systems only reduce disk read/write contention without really solving the cause of disk contention. Simulations using the Sprite traces are used to guide the design of a client and server caching protocol for the Pegasus File Server (PFS). This protocol guarantees data persistency, without writing the data to disk, through replication