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Best way to securely erase my entire MBP HDD?

E

EricVT

macrumors member
Original poster
Feb 19, 2008
64
0
Hi folks.

Recently agreed to sell my early 2008 MBP and I want to do a completely clean install of OSX before handing it off, including securely erasing all of the contents of my current HDD. I don't know what sorts of personal information might be buried away in my computer (emails, Safari and Firefox passwords, etc..)

I don't think that this person would attempt to recover that information or anything, but you never know and I guess I am also thinking about anyone else down the line that gets their hand on the computer that I don't know personally. Maybe I'm being a bit paranoid but better safe than sorry.

What's the most headache-free way to go about doing this?
 
When you boot your MBP from the install disk. Start disk utility and there is an option to write random ones and zeros 35 times to the entire drive...

Note: It will take a lot of time... probably a whole night.
 
There is also an option for doing it only once and seven times, as 35 times might be too much. To recover data from that, one would have to have access to quite an expensive equipment.
Once o seven times zeroing out the HDD will suffice.

2489810109_98a3a367e8_o.png
 
Do those methods overwrite the data, or just "the data used to access your files"?
 
flaneur said:
Which data?

Do you know?

Do you see my point?
Click to expand...

Data depends on what you delete.

If you delete a folder and securely empty the Trash, which means the folder is being overwritten once, seven or 35 times, the term data is relating to that folder.

If you delete an entire partition/volume/hard disk drive and use the Secure Erase Options, and all the files and all the folders are being overwritten once, seven or 35 times, the term data relates to all files and folders on that HDD, meaning all data.

data |ˈdatə; ˈdātə|
noun [treated as sing. or pl. ]
facts and statistics collected together for reference or analysis. See also datum .
• Computing the quantities, characters, or symbols on which operations are performed by a computer, being stored and transmitted in the form of electrical signals and recorded on magnetic, optical, or mechanical recording media.
• Philosophy things known or assumed as facts, making the basis of reasoning or calculation.
ORIGIN mid 17th cent. (as a term in philosophy): from Latin, plural of datum .
USAGE Data was originally the plural of the Latin word : datum, 'something (e.g., a piece of information) given.' Data is now used as a singular where it means 'information': : this data was prepared for the conference. It is used as a plural in technical contexts and when the collection of bits of information is stressed: : all recent data on hurricanes are being compared. Avoid : datas and : datae, which are false plurals, neither English nor Latin.
 
Spinnerlys, that's what I was getting at: does it delete the data or the data used to access the data (I come from a Windows background, and I don't know the Mac terminology: I was asking whether it deletes the data itself or merely the FAT).

Thanks.
 
flaneur said:
Spinnerlys, that's what I was getting at: does it delete the data or the data used to access the data (I come from a Windows background, and I don't know the Mac terminology: I was asking whether it deletes the data itself or merely the FAT).

Thanks.
Click to expand...

See the above-posted graphic. The 1, 7, and 35 times options clearly state they write zeros over the data used to access the data ("FAT") as well as the actual data as well.
 
flaneur said:
Spinnerlys, that's what I was getting at: does it delete the data or the data used to access the data (I come from a Windows background, and I don't know the Mac terminology: I was asking whether it deletes the data itself or merely the FAT).

Thanks.
Click to expand...

2489810109_98a3a367e8_o.png


Everything except the Don't Erase Data option overwrites, and therefore deletes, all the data that is on the HDD, not just the partition table, which is what the Don't Erase Data option does only.

If you have a 232GiB (250GB) HDD with 194GiB of data, it will write ones and zeros to fill those 194GiB once, seven or 35 times, depending on what option you choose.
Therefore it takes time, more time or a really long time, depending on the average writing speed.
194GiB will take 66 minutes, 462 minutes or 2310 minutes (1.6 days) on a drive that offers at least an average write speed of 50MB/s.
 
iMav said:
See the above-posted graphic. The 1, 7, and 35 times options clearly state they write zeros over the data used to access the data ("FAT") as well as the actual data as well.
Click to expand...

Well, only if you don't understand Latin.
 
thatguysmells said:
Why can't you just insert the osx disk and click erase and install?
Click to expand...

Erase and Install
This option completely erases the destination volume, then installs a new copy of Mac OS X. You should always back up important files on the target volume before using this type of installation.

This is the fastest way to install Mac OS X, but it may take some time to set up your computer after installation. You will have to configure all of your computer settings, install your third-party and iLife applications, and restore your personal files from the backup you made.

Why use this option?

If you've already backed up your computer, this might be a good choice if you are trying to resolve an existing issue and an Archive and Install installation didn't help.
This option takes up the least amount of space when the installation is completed.
This is a good option if you no longer need the information on the computer, and you have another computer that you would like to easily transfer stuff from ("migrate").
Volume format choices
Once you've selected this option, you can choose from two types of volume formats:

Mac OS Extended (Journaled)—This is the default option and should be used unless you have a specific reason not to.
UNIX File System—Only choose this option if you specifically need it.

Does an Erase and Install change partition configurations?
No, it uses the current settings. It also doesn't configure advanced RAID settings or perform a secure erase. If you want to do any of these things, use Disk Utility before installing; you can access Disk Utility while started from the Install disc.

found on http://support.apple.com/kb/HT1545
via http://www.google.com/search?client=safari&rls=en&q=erase+and+install&ie=UTF-8&oe=UTF-8
 
spinnerlys said:

Erase and Install
This option completely erases the destination volume, then installs a new copy of Mac OS X. You should always back up important files on the target volume before using this type of installation.

This is the fastest way to install Mac OS X, but it may take some time to set up your computer after installation. You will have to configure all of your computer settings, install your third-party and iLife applications, and restore your personal files from the backup you made.

Why use this option?

If you've already backed up your computer, this might be a good choice if you are trying to resolve an existing issue and an Archive and Install installation didn't help.
This option takes up the least amount of space when the installation is completed.
This is a good option if you no longer need the information on the computer, and you have another computer that you would like to easily transfer stuff from ("migrate").
Volume format choices
Once you've selected this option, you can choose from two types of volume formats:

Mac OS Extended (Journaled)—This is the default option and should be used unless you have a specific reason not to.
UNIX File System—Only choose this option if you specifically need it.

Does an Erase and Install change partition configurations?
No, it uses the current settings. It also doesn't configure advanced RAID settings or perform a secure erase. If you want to do any of these things, use Disk Utility before installing; you can access Disk Utility while started from the Install disc.

found on http://support.apple.com/kb/HT1545
via http://www.google.com/search?client=safari&rls=en&q=erase+and+install&ie=UTF-8&oe=UTF-8
Click to expand...

What's the difference between erasing the disk and securely erasing the disk? :confused:
 
thatguysmells said:
What's the difference between erasing the disk and securely erasing the disk? :confused:
Click to expand...

I knew it.

2489810109_98a3a367e8_o.png

three times is a charm, and can one bold an image?


Erasing normally just deletes the pointer to a file, securely erasing means that the file is overwritten with 1s and 0s.

That is done as not to put too much strain on HDDs, as securely erasing is a writing activity like any other, which reduces the life time of that mechanical device.
Plus most people can't even restore normally erased data (when the Trash/Recycle Bin has been emptied) without the help of extra software.
 
Once you complete the software erasure methods described above you may avail yourself of any or all of the final hardware solutions listed here.

Remove the disk from the Mac, clamp it to a work bench and drill many, many holes through the entire disk being careful to capture any and all shavings.

Take ventilated disk and shavings and place in smelter. Melt entire disk down to molten metal and silicone.

Boil off all non metallic residue and pour molten metal into 100 tiny spherical casts being sure to remove all residue from smelter.

Remove 100 cooled metal balls. Encase Metal balls into small hot glass figurines shaped like square safes.

Ship figurines to 99 friends, family, and customers, etc as unique gifts, keeping one as a testament to your thoroughness.

Only then will you be certain your data can NEVER be retrieved.

Cheers,
 
panzer06 said:
Once you complete the software erasure methods described above you may avail yourself of any or all of the final hardware solutions listed here.

Remove the disk from the Mac, clamp it to a work bench and drill many, many holes through the entire disk being careful to capture any and all shavings.

Take ventilated disk and shavings and place in smelter. Melt entire disk down to molten metal and silicone.

Boil off all non metallic residue and pour molten metal into 100 tiny spherical casts being sure to remove all residue from smelter.

Remove 100 cooled metal balls. Encase Metal balls into small hot glass figurines shaped like square safes.

Ship figurines to 99 friends, family, and customers, etc as unique gifts, keeping one as a testament to your thoroughness.

Only then will you be certain your data can NEVER be retrieved.

Cheers,
Click to expand...
Just in case the OP does this, do NOT send the balls out. They could retrieve the data off them.

Thanks.
 
What about just modifying the original file that you want inaccessible? For example, I have a sensitive Excel doc, which I completely replace the information with gibberish. Does this work? Would the first version of the file sill be retrievable?
 
applebook said:
What about just modifying the original file that you want inaccessible? For example, I have a sensitive Excel doc, which I completely replace the information with gibberish. Does this work? Would the first version of the file sill be retrievable?
Click to expand...

It's possible yes. Best to erase as noted above.
 
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