In high-performance scientific computing, users output millions of files per project or simulation, resulting in petabytes of information. Little is known how users make sense of it all, and what the major usability issues are in interacting with a file system at scale. We conducted interviews with scientists at national laboratories to identify common practices and issues with current peta-scale file system usage. Scientists' most-reported priorities in file system interaction were command-line interface compatibility, remote access, speed, and freedom. The major usability problem encountered in the interviews was the purge threat, triggered when the parallel file system reaches capacity, with other usability problems including file lookup, issues related to system performance, and trusting the system. We define reactionary and cautionary archiving and draw a parallel between archiving methods and data production paradigms. We present three methods scientists used to address the purge threat, discuss how subversion of the purging system is a clear indication of its lack of utility, and propose two non-hierarchical file and directory representation models to address the purge threat.