Performance Analysis of the PVFS2 Persistency Layer

                         Julian Kunkel


                            Abstract

In this thesis the persistency layer of the Parallel Virtual File
System 2 (PVFS2) is analyzed in order to argue about the limitations
in the architecture. Therefore, a new module is introduced that
replaces the current module responsible for the persistency
layer. This module operates in memory and provides an upper bound for
the achievable performance of the persistency layer.

The basics of the persistency layer and the internal request
processing are documented to help the reader to understand the
servers' workflow. Some simple theoretical thoughts lead to estimated
upper bounds for the performance of various operations. These
estimated upper bounds are later compared with measured performance
values.

Different benchmarks are run to determine the I/O and the metadata
performance of several configurations. The measured data is evaluated
and discussed in orderto improve the implementation. Within the
framework of the thesis some bottlenecks could already be found. It
turns out that there is much room for further improvement in the
metadata handling of PVFS2.