84 High Performance Parallel I/O
7.2.2 Parallel File Systems—A Shared Resource
Often, ideal measurements, taken under ideal conditions, are the type that
are used to quote file system performance for a given system. However, from a
user perspective, it is important to understand that these peak numbers may
not be indicative of the level of performance they can expect to achieve in
a multi-user, production system environment. Indeed, on most modern HPC
systems, the file system is truly a shared resource; one in which the instan-
taneous performance is influenced by how many users are accessing the file
system and what type of workloads they are performing. Consequently, when
estimating application runtime requirements, users are recommended to pad
the I/O ...