Scrub That Disk Clean! -A little conscientious use can really pay off

摘要

We have previously addressed how files are stored on disk media, with particular emphasis on systems running the MS Windows and DOS operating systems. As you may recall, at that time we were particularly interested in recovering files that had been deleted or were lost due to disk corruption errors. We were able to do this because these systems did not actually delete the files when you clicked "Delete" or dragged them to the recycle bin. All the system did was mark the space as available in the system's disk allocation table, the map that shows what part of the disk is being used. The actual data remained on the disk and, with the proper tools, was available to anyone who knew how to access it until it was actually overwritten when the operating system wrote another file to the disk. For recovery purposes, the picture was even better with some of the newer operating systems, as they attempted to avoid reusing the area where deleted files existed until they'd run out of additional space on the drive, after which the released space would be recycled and overwritten.