10 Replies Latest reply: Apr 4, 2011 10:30 AM by WZZZ
AndyGump Level 1 Level 1 (5 points)
I would like to transfer ownership of my iMac to my daughter, what needs to be done to make it so that there is no trace of me, (account names, passwords, etc.), in the computer? Can that be done?

Andy

iMac4,1, Mac OS X (10.6.7), 2 GB DDR2 SDRAM, otherwise standard machine
  • Niel Level 10 Level 10 (282,095 points)
    Use its original disks to perform an Erase & Restore.

    (57446)
  • AndyGump Level 1 Level 1 (5 points)
    My computer is an early 2006 Intel model so going back to the original disk and starting there to get it up to today's configuration leaves the following question. I am now at OS version 10.6.7, can I load the original Snow Leopard over the original disk from back in 2006 and then update from Apple and be up to date at 10.6.7? If that is the case then I can build the remainder of the system from other sources, correct???

    Thanks for your help

    Andy
  • Niel Level 10 Level 10 (282,095 points)
    Yes to both questions.

    (57448)
  • AndyGump Level 1 Level 1 (5 points)
    Thanks, that seems straight forward enough to me.

    Another question, when I move to another iMac what do do I need to do about my Time Machine disk? Will it switch over automatically when I attach it to the new computer?

    Andy
  • AndyGump Level 1 Level 1 (5 points)
    I tried the following; I tried to start with the Install disks that came with the computer and all I would be allowed do there was to install the original OS 10.4.4 software, apparently in the available free space. I didn't get the impression that the disk would be otherwise modified, next I went to Disk Utility and was going to erase the MacIntosh HD but I wasn't allowed to do the erasure. What am I not understanding about the procedure to initialize the HD, as it would look coming from the factory?

    Andy
  • babowa Level 7 Level 7 (27,700 points)
    I'm not as knowledgeable as Niel, but let's see if I can help here:

    When you use the install disk to boot from, you will see the Installer. Get past the language selection and then go to the menu bar and choose Utilities. Choose Disk Utility, highlight your drive and choose erase. You can do a simple erase or go to Options and choose a 7 pass erase (that means it will write zeroes on the hard drive seven times - a good idea when you are getting it ready to sell or give to someone else). Once the hard drive has been erase - be patient, a 7 pass will take a few hours - quit Disk Utility and let the installer do its thing.
  • WZZZ Level 6 Level 6 (12,755 points)
    Not necessary Barbara. Big time waster. A 7 pass on a 500GB drive may, depending on the speed of the processor, take up to a full day (24 hours) or even more. Zero one pass is completely sufficient.

    +*Secure deletion: a single overwrite will do it*+

    +The myth that to delete data really securely from a hard disk you have to overwrite it many times, using different patterns, has persisted for decades, despite the fact that even firms specialising in data recovery, openly admit that if a hard disk is overwritten with zeros just once, all of its data is irretrievably lost.+

    +Craig Wright, a forensics expert, claims to have put this legend finally to rest. He and his colleagues ran a scientific study to take a close look at hard disks of various makes and different ages, overwriting their data under controlled conditions and then examining the magnetic surfaces with a magnetic-force microscope. They presented their paper at ICISS 2008 and it has been published by Springer AG in its Lecture Notes in Computer Science series (Craig Wright, Dave Kleiman, Shyaam Sundhar R. S.: Overwriting Hard Drive Data: The Great Wiping Controversy).+

    +They concluded that, after a single overwrite of the data on a drive, whether it be an old 1-gigabyte disk or a current model (at the time of the study), the likelihood of still being able to reconstruct anything is practically zero. Well, OK, not quite: a single bit whose precise location is known can in fact be correctly reconstructed with 56 per cent probability (in one of the quoted examples). To recover a byte, however, correct head positioning would have to be precisely repeated eight times, and the probability of that is only 0.97 per cent. Recovering anything beyond a single byte is even less likely.+

    +Nevertheless, that doesn't stop the vendors of data-wiping programs offering software that overwrites data up to 35 times, based on decades-old security standards that were developed for diskettes. Although this may give a data wiper the psychological satisfaction of having done a thorough job, it's a pure waste of time.+

    +Something much more important, from a security point of view, is actually to overwrite all copies of the data that are to be deleted. If a sensitive document has been edited on a PC, overwriting the file is far from sufficient because, during editing, the data have been saved countless times to temporary files, back-ups, shadow copies, swap files ... and who knows where else? Really, to ensure that nothing more can be recovered from a hard disk, it has to be overwritten completely, sector by sector. Although this takes time, it costs nothing: the dd command in any Linux distribution will do the job perfectly.+

    http://www.h-online.com/newsticker/news/item/Secure-deletion-a-single-overwrite- will-do-it-739699.html
  • babowa Level 7 Level 7 (27,700 points)
    Interesting - that's the first time I heard that a one-time pass is good enough - that'll save considerable time!
  • AndyGump Level 1 Level 1 (5 points)
    Thanks to everyone for the help, this was my first time at this process and wasn't sure what to do. I finally got the job done and things are working fine. Apparently my hangup was not understanding how to get to the erase and install part of the process but when I did the answer that I was looking for was clear to me so I proceeded.

    Regarding the erasing of memory, I can't imagine that today's technology has a need to write zeros or ones repeatedly to erase all evidence of what was once there, maybe when memory was magnetic cores but not today.

    Thanks again

    Andy
  • WZZZ Level 6 Level 6 (12,755 points)
    It's still magnetic, at least for conventional hard drives.