Lawrence Berkeley National Laboratory

The Franklin Cray XT4 at the NERSC center was equipped with the server-side I/O monitoring infrastructure Cerebro/LMT, which is described here in detail. Insights gained from the data produced include a better understanding of instantaneous data rates during file system testing, file system behavior during regular production time, and long-term average behaviors. Information and insights gleaned from this monitoring support efforts to proactively manage the I/O infrastructure on Franklin. A simple model for I/O transactions is introduced and compared with the 250 million observations sent to the LMT database from August 2008 to February 2009.