Duplicate files have the potential to use a lot of space on your hard drive, and many of the duplicate files are not necessary. Identifying duplicate files, however, can take a lot of processing.
DiskFerret identifies duplicate files by comparing one or more of the following; name, size, date, or CRC-32. You can specify the criteria you prefer in the Duplicate File Options dialog. When CRC-32 is specified, DiskFerret will 1st use other criteria, if specified, to identify duplicate file. When it finds a file name, size or date that matches, it reads both files and computes a 32-bit cyclic redundancy check (CRC-32) for each of them. Donít worry if you donít know what a CRC algorithm does, most people donít. It is a commonly used technique used in software to detect differences in data streams. The CRC algorithm is very fast, however, reading the files from disk is relatively slow in comparison, and reading the files from disk takes a lot longer than DiskFerretís normal scan task of getting the name, size and date from the file system.
Computing CRCís can take an especially long time if DiskFerret finds many files to compare (i.e., files with the same name, date, or size) or, if you specify CRC as the only criteria, which will cause every fileís CRC to be computed (not recommended unless you have a special need). For these reasons, Disk Ferret does not attempt file comparisons on a normal scan. Instead, the duplicate files data view toolbar provides a separate start button (circled in red below) to scan for duplicate files. After a normal scan for a folder has been performed, this start button is enabled and you must click the button to perform a check for duplicate files.
The duplicate file scan displays a progress indicator as it does with a normal scan. When the scan is complete you can use the pie chart, bar chart and table view as in other data views. However, one difference is that the table view in the duplicate files data view is actually a Table Tree View which is a combination of a table view and a tree view. See the ďUsing the Table Tree ViewĒ section for information how to use a table tree.