what is the best way to clear the info on my computer?

[djvampy]

hi everyone i have a few questions and was hoping someone could help or give some advice here. i am selling my macbook in the hopes in getting an Imac. what im wondering is what is the best way to clear the info on my computer? would it be the discs that came with the machine to reinstall the OS? or should i use the 35 times disk write that is in the utilities. or both methods even?? any help would be greatly appreciated, thanks!

 

[pigoo3]

what im wondering is what is the best way to clear the info on my computer? would it be the discs that came with the machine to reinstall the OS? or should i use the 35 times disk write that is in the utilities. or both methods even?? any help would be greatly appreciated, thanks!

If memory serves me correctly....using Disk Utilities secure erase feature...you can do a 1, 7, or 35 times pass where zeros are written to the hard drive.

Personally I just use the single pass. Obviously a 7 time pass will take 7x longer...and the 35 times pass will take 35x longer. On a large hard drive...that is a LONNNGG time!

So I would recommend the single pass secure erase...then you could reinstall the Mac OS of your choice afterwards before selling the computer. You could do a 7x pass if you want to & have the time.

Hope this helps,

- Nick

 

[EndlessMac]

would it be the discs that came with the machine to reinstall the OS? or should i use the 35 times disk write that is in the utilities. or both methods even??

You have the general idea. Boot off the Mac OS disc and the feature you are talking about should be in Disk Utility. A 35 times zeroing the hard drive is rather overkill and unless you have top secret government files and have a lot free time then a one pass should be good. I believe there is a 7 pass feature and it's up to you if you want to take the time to do so. Reinstall the OS once you are done and then it's good to sell.

edited: pigoo3 beat me to it

 

[pigoo3]

edited: pigoo3 beat me to it

Brilliant minds think alike!

 

[EndlessMac]

Brilliant minds think alike!

Apparently you don't know me that well. LOL

 

[djvampy]

thanks everyone for the advice. so basically take the files from the hard drive, put them in the trash basket icon, empty the basket, and then when everything is erased THEN do the 7 - 35 times overwrite? and then use the install disk?

 

[pigoo3]

thanks everyone for the advice. so basically take the files from the hard drive, put them in the trash basket icon, empty the basket, and then when everything is erased THEN do the 7 - 35 times overwrite? and then use the install disk?

You don't even need to drag the files to the trash. The "overwrite" of the hard drive will write-over all of your files...erasing them completely.

You can do a 1x, 7x, or 35x overwrite.

Then use the install disk to install the OS.

By the way...you have to boot with the install disk to do the overwrite.

- Nick

 

[djvampy]

thx for the advice guys basically booting with the install disk is just starting the machine up with the install disks in? or do i have to boot with the disk in and hold a button down? i thought i read about that somewhere once but cant remember.

 

[EndlessMac]

thx for the advice guys basically booting with the install disk is just starting the machine up with the install disks in? or do i have to boot with the disk in and hold a button down? i thought i read about that somewhere once but cant remember.

You need to hold down the C key when booting up with the disc inside.

 

[djvampy]

thanks both of you for the advice, appreciate it. i will be doing this later this week. im hoping it all goes well

someone i was talking to about computers was telling me that disc recovery software could still restore files even with an overwrite. im just concerned about credit card info i have done for purchases and such. never can be to safe i suppsose lol. is he right that disk recovery software could even recover a 7 X overwrite?!

 

[6string]

Once you boot off the install disc, erase the HD and proceed with installation of the new OS, even without overwriting 1, 7, or 35 times........ it would cost $1000's for a professional recovery service, to get anything, and even if they did (which they wouldn't), there would only be fragmented bits of incomplete data!
Save yourself the effort, and if you are in doubt, just 0 over 1x.

 

[chas_m]

I just want to mention that for anything other than the 1-pass erase, we are talking a VERY VERY long time here. The last time I did a seven-pass, it took TWO DAYS. I've heard stories of 35-pass runs that took over A WEEK (that's 24-7!).

Consider yourself warned. Zeroing out the drive should be more than sufficient unless you are working for the CIA.

 

[6string]

I just want to mention that for anything other than the 1-pass erase, we are talking a VERY VERY long time here. The last time I did a seven-pass, it took TWO DAYS. I've heard stories of 35-pass runs that took over A WEEK (that's 24-7!).

Consider yourself warned. Zeroing out the drive should be more than sufficient unless you are working for the CIA.

Or if you think the CIA or FBI are working on you!

 

[djvampy]

i appreciate the advice everyone, thanks. First time posting on this site and its been very helpful!

 

[djvampy]

hmmm under disk utilities under the 1 - 7 - 35 overwrite, part of it is grayed out. like i cant select the erase option. anyone know what im referring to?

 

[6string]

Are you booted from your install disc?
Are you selecting Macintosh HD (under the size and name of the HD) in the left column?

 

[Head_Unit]

From what I had researched, in a Unix environment the trash is not so easy to recover, and "secure trash" very difficult. I don't know about for the NSA, but for any normal buyer. So you can do an overwrite but maybe not so necessary.

If that's incorrect, I'd like to know...

Or, you could just swap for a new HD and keep the original as a backup.

 

[dcow]

well.. the VERY best way to erase a drive is with a hammer (=

You need to be booting off a disc to erase your system partition.

 

[6string]

From what I had researched, in a Unix environment the trash is not so easy to recover, and "secure trash" very difficult. I don't know about for the NSA, but for any normal buyer. So you can do an overwrite but maybe not so necessary.

If that's incorrect, I'd like to know...

Or, you could just swap for a new HD and keep the original as a backup.

Basically emptying the trash is hard enough to retrieve, especially if the computer has been used since emptying the trash, as overwriting has already occurred. Secure trash takes that a step further and overwrites on the spot.
Going to the next level, reinstalling an OS, you can say goodbye to pretty much everything as far as Data Recovery of any sort goes, and erasing the hard drive before reinstalling the OS, there is really no chance of retrieving anything.
Zeroing out a drive before installing an OS is pretty much overkill, and I think is something that should be left to banks, criminals such as pedophiles, secret agents, etc
The reason obviously that even the smallest bit of incriminating fragmented information found by the FBI, CIA, KGB, etc found may be all that is required.

 

[dcow]

Basically emptying the trash is hard enough to retrieve, especially if the computer has been used since emptying the trash, as overwriting has already occurred. Secure trash takes that a step further and overwrites on the spot.
Going to the next level, reinstalling an OS, you can say goodbye to pretty much everything as far as Data Recovery of any sort goes, and erasing the hard drive before reinstalling the OS, there is really no chance of retrieving anything.
Zeroing out a drive before installing an OS is pretty much overkill, and I think is something that should be left to banks, criminals such as pedophiles, secret agents, etc
The reason obviously that even the smallest bit of incriminating fragmented information found by the FBI, CIA, KGB, etc found may be all that is required.

Actually, the reason behind a 35pass write is a little more practical than you'd think. The idea is that each 'bit' on a hard drive is like a magnetic "box" it's a little square portion of the harddrive that gets flagged as '1' or '0' by the head. This is a write. Now the head, it turns out, is not very accurate and it has a relatively big 'box' that it writes a much smaller 'bit' to. If you have a drive with a bunch of data on it, and you simply zero out the data, with the right tools, it's is actually very easy to analyze that zeroed out disk, and see where all the ones used to be. That's the general idea, it's a little more complicated than that (turns out you can even detect where original data used to be after say 3 or 4 passes [which is the idea behind a 7 pas overwrite] and the only way to have your data 99.99 percent unrecoverable is to write over it 35 times) but you get the idea. If I was selling my harddrive and I had sensitive information on there then there is no reason not to be cautious.