PCP Disk Requirements -- J. White reported that PCP
development has progressed to the point of designing the disk
allocation layout for the processing of each scan. Each PCP (Pipeline
Control Processor) processes a single scan at a time, and each CPU on
each production machine (two machines, four CPUs each) will run one PCP
during the corresponding phase of the 2MAPPS execution. In order to
meet the goal of reducing I/O contention between PCPs, the current
design for each production machine calls for three input volumes (one
per band), four scratch volumes (one per CPU/PCP), and two output
volumes, hence nine disk volumes per machine. This is a change from the
previous requirement for eight disk volumes per machine; R. Cutri will
inform R. Scholey of the increased requirement. If CPUs are added to
a production machine with the intention of running more PCPs, then one
additional disk volume per additional CPU will also be required.
R. Beck reported that for testing in the near term, one karloff
disk volume could be used as a ninth lugosi volume (assuming PCP
testing on lugosi), but the karloff disk should be used as an input
volume, since reads across the karloff-lugosi connection are
significantly faster than writes.