A few days ago a friend asked me what the difference was between performing a quick format and a regular format. First thing I should mention here is that we are talking about used drives, so ‘reformat’ is probably the more precise term. Anyway, technology is not my forte by any means but I relayed what I knew in layman’s terms which satisfied my friend, but also made me realize my own understanding of the processes was pretty limited. So I decided to research the subject and expand my knowledge in this area.
First thing I noticed; there is a heck of a lot of misunderstanding and misconception about what actually happens during a reformat; much of which can be attributed to changes Microsoft adopted for Vista. Pre Vista operating systems, including XP, handle the Quick Format in much the same manner but the Regular Format changed in Vista and those changes carried through to Windows 7.
Unfortunately, many sources are still quoting the older information relevant to XP, even though they are discussing Vista/Win7. This, of course, not only confuses the issue but also makes it pretty difficult to get a handle on. After much research, this is what I have come up with:
Does not actually overwrite, delete or erase any existing data. A Quick Format simply creates a new master file table (MFT), which subsequently renders any existing data unreadable/inaccessible. The MFT lets the system know where files are on the disk, sort of like the index section of a book, because the new MFT doesn’t reference existing files they cannot be accessed. All the existing files are still there and can be quite easily resurrected using fairly basic data recovery software.
Pre Vista: Is exactly the same as the Quick Format except it also checks the drive for any bad sectors (same as running chkdsk /r). Existing data is not overwritten or erased and the extra time involved is totally taken up by the disk checking function.
Vista & Windows 7: Actually performs a rewrite pass over the entire drive. This adds a level of security to the process and provides a cleaner starting point for fresh data.
*Please be aware that the Regular Format’s one pass rewrite is adequate for disks which are being retained/re-used but definitely not secure enough for disposal. If you are passing a hard drive on, you will need to use software which performs multiple rewrite passes in order to render the data pretty much unrecoverable. In fact, if you are discarding a hard drive altogether, then I would suggest smashing the heck out it with a hammer first…very secure and great fun too!!