Question Details	Asked By	Asked On
Erasing Hardrive	JCB269	02/29/04
I would like to sell my computer and want to erase the hardrive so no information can be extracted from it that may have come from saved documents of mine, or internet usage which may have involved credit card numbers and what not. I hear that this information cannot be wiped from the hardrive easily. Is this accomplished by reinstalling OS X, and choosing the option " hardrive and reinstall," or is some other method necessary?
Answered By		Answered On
voiceguy2000		02/29/04
As you are probably aware, when a computer file is "deleted" the magnetic information on the disk is not actually altered; rather, the sectors on the disk where the file resided are marked as "available" for the writing of new files. Until a new file overwrites the old one, the old file is there in pristine form. That is why "undelete" utilities work; they simply restore the "in use" status of a file, and as long as nothing new has been written over the sectors that the old file had used, everything will still be right there. In order to prevent others from peeking at your old files, the most effective step is to use a "wipe" utility. This will actually write new data over all the unused sectors on the disk (including sectors containing old files that are marked as "deleted"). Government standards typically call for three passes of overwriting to try to minimize any "residue" of old information. The last time I looked, Norton Utilities included a "WipeDisk" module that will accomplish this. There are also shareware utilities such as MacWasher X that you could try. I would recommend the format-and-reinstall option for OS X, followed by a disk-wiping utility. That should give you peace of mind.

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