Described is a method and system by which reports of storage usage in
computer systems are generated in an efficient manner by consolidating
multiple requests for reports into a minimal number of volume scans,
including by intelligently selecting a scanning method (e.g., of file
system metadata versus find-first/find-next) and by performing parallel
scans on different volumes. Namespace consolidation scans namespaces
together, so as to generate multiple reports from the same set of files,
reducing the number of volumes scans required to collect the data. Each
volume scan may be a find-first, find next directory-based scan, or a
volume metadata database scan. Time consolidation groups independent
storage report generations together, such as storage report requests
received within an administrator-specified interval. Parallel scans of
different volumes may be performed, subject to I/O and processing
resource limitations, and so that volumes partitioned on the same spindle
are not scanned in parallel.