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Zeroing Out Mac Drives
Misanthropic
Registered User regular
Registered User regular
Can someone suggest me a good (and free) tool for Mac OS X that will zero out some hard drives? Going to be selling two Macs soon and would like all my personal data off the drives.
Thanks.
Thanks.
Misanthropic on
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Maybe connect the Macs up as Firewire drives then blitz them.
It has 3 options
Zero Out Data - erases, writes over everything once with zero's
7-Pass - writes over everything 7 times
35-pass - 35 write overs
I've always wondered why they have these options. I mean, if you write over everything with a zero, all the data is gone, right? That shit is blank! So uh... why spend the time doing it 7 or 35 more times? Is that for the ultra-paranoid? o_O Or maybe I just don't know enough about hard drives?
Drive platters can retain a residual charge, even after being overwritten several times. Thirty five seems a bit excessive, but maybe some government buyers require such measures.
in the 7-pass description says thats what the government uses.
35-pass is kinda nuts though
But at minimum I'd do the 7-pass. 1-pass is too easy to recover data from.
And then remember afterwards to reinstall OSX onto the drive, unless you bought it seperately as an upgrade.
People are allowed to create threads about topics similar to your pet thread's topic, asshole.
CUZ THERE'S SOMETHING IN THE MIDDLE AND IT'S GIVING ME A RASH
Most data recovery places are just looking for files that have been deleted or the remnants of a drive after a head crash. They don't actually have the tools or skills to look for residual data after a wipe. The sort of labs capable of that sort of work are decidedly rare in the consumer industry and yet even more expensive than the normal professional data recovery labs. Unless you've been up to some seriously bad shit and the FBI is going to kick your door down tomorrow, it doesn't really matter beyond the first re-write pass.
Don't get me wrong, absolutely do a full re-write, and using random data is better than 0s and takes no extra time. Don't just format the drive and assume that this means the data can't be recovered because a format is trivial to recover data from, there's relatively cheap software that'll do the task. But anything beyond a single pass is a waste of time if you don't have state secrets on your hard drive.
EDIT: The reason I'm saying this is that your identity, your bank accounts, your credit history, the whole works? It's worth less than it would cost in time and money to recover a drive that's been completely wiped that way. And the contents of your drive probably don't even have enough information to give a thief that sort of access to your identity anyhow. It would be completely insane to go to that effort and spend that kind of money on speculation that some hard drive that was purchased second hand might possibly contain enough info to steal your identity.
CUZ THERE'S SOMETHING IN THE MIDDLE AND IT'S GIVING ME A RASH
Uhm... ok? It's not exactly my pet thread, and for once I wasn't even aggressive with the request. I thought it also might help get his question answered more quickly, since it was Mac specific. Sorry for trying to keep the forum clean.
When Tube starts huffing glue and decides to make you a mod you can go ahead and try to keep the forum clean.
CUZ THERE'S SOMETHING IN THE MIDDLE AND IT'S GIVING ME A RASH
Wow. Whatever dude.
Alright, SO, after writing over a disc with zero's once, the platter can retain a residual charge. That makes multiple wipes less silly. But, what I don't get is, what exactly is this residual charge? Like, if you were to select one bit at random, it would be a zero, but you could possibly tell that it used to be a one? That blows my mind. Am I understanding this correctly?
Although computers read discs as zero and one, the actual physical platters can contain a range of charges. Maybe it starts at 0, you write a one and now it's 0.95, you write a zero and it's now 0.10. Depending on the pattern of data written and the technology available, it's theoretically capable to recover data from a drive.
Remember that drive security isn't related to just what technology is available right now. Some information, like financial or medical records, have an inherent value that might persist for decades (eg, the life of a patient). That's why stuff like 35-time writes exists -- although it is gross overkill today, maybe tomorrow it will be barely enough. Same philosophy as encryption -- protection is measured in half-lives.
As an aside, in the US that isn't enough. if a HDD has medical records on it, it's usually smelted or stays in a building locksafe and never leaves the premises. HDD companies will handle RMAs from hospitals by only requesting the faceplate.
I work at a dental office, if the drive has had confidential stuff on it we just toss it into what is effectively a woodchipper.
Oh, I just remembered that pic my dad sent me of a wanged drive he sent away for data recovery.
The recovery guys sent a picture back. The drive head had scratched away all the metal from the drive platters leaving just glass disks. :P
edit: here it is. That's one drive you won't recover any data from.
Wow, you guys deal well with confidential stuff.
In the UK it's customary to leave it all on CDs in a public place. Unencrypted. Ideally with "Top Secret" written on it. If you're a government official in any case.
Nice, looks like a next gen vinyl replacement :P
http://dban.sourceforge.net/
Not on a Mac.
That'll work fine on a mac, actually, both PPC and Intel.
Thats what I do (and I don't leave bank data on a computer anyways). An encrypted image file which also contains misc data of several GB (movies, game installation) etc., so that nobody could "snag" the file easily and have their way with it.
So why does this exist?
Better safe than sorry, just use the OS X install disc. You already have this anyway if you have a Mac.
This is pretty amazing.
There is not a person on these boards capable of restoring from a 1-pass erase. Its not even slightly easy.
猿も木から落ちる
That link is to a page stating that DBAN supports macs, which proves my point.