Abstract: Described is a storage reports duplicate file detector that operates by receiving file records during a first scan of file system metadata. The detector computes a hash based on attributes in the record, and maintains the hash value in association with information that indicates whether a hash value corresponds to more than one file. In one implementation, the information corresponds to the amount of space wasted by duplication. The information is used to determine which hash values correspond to groups of potentially duplicate files, and eliminate non-duplicates. A second scan locates file information for each of the potentially duplicate files, and the file information is then used to determine which groups of potentially duplicate files are actually duplicate files.

Abstract: 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.