The performance of parallel distributed file systems suffers from many clients executing a large number of operations in parallel, because the I/O subsystem can be easily overwhelmed by the sheer amount of incoming I/O operations. This, in turn, can slow down the whole distributed system.

Many optimizations exist that try to alleviate this problem. Client-side optimizations perform preprocessing to minimize the amount of work the file servers have to do. Server-side optimizations use server-internal knowledge to improve performance.

This paper provides an overview of existing client-side optimizations and presents new modifications of the Two-Phase protocol. Interleaved Two-Phase is a modification of ROMIO's Two-Phase protocol, which iterates over the file differently to reduce the number of seek operations on disk. Pipelined Two-Phase uses a pipelined scheme which overlaps I/O and communication phases to utilize the network and I/O subsystems concurrently.