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Ye Macce Threade


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...my older 2005 tablet pc won't boot from a USB drive and doesn't have CD drive. 

That might be a BIOS setting -- sometimes it's set so that the hard drive boots first, I.E. always unless it fails.  Go into the BIOS settings and look for something like "boot order".  Sometimes it's order, sometimes it's on/off, sometimes it's other things.

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I realized that I have to erase the hard drive on Tim's most recent computer (2014 MBP) which has a SSD drive.  The problem is that I have to give the laptop back to the department and I believe they are going to use the laptop.  I think it needs to include the SSD and even if not, I am not sure how easy it is to get the SSD out of the computer. 

 

Is there a way to securely erase an SSD without physically destroying it?  I have read that encrypting doesn't work nor does writing over with zeros.  :(

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It would be much better for a random person to try to reconstruct the data because he has letters of recommendation for students who are current grad studetns, postdocs and former students (these are exactly the people who are going to have access to the computer).  While it is unlikely they would do this, graduate students in math have been known to spend endless hours doing something just because they can (and some have backgrounds in computer science).  

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I think wiping it with zeroes would be 100% fine, but only if you do the whole drive and not just the index/contents section.  Some programs out there will do multiple passes, too.  Not sure what is out there for Mac Wiping SW, but I have had no issues with wiping PC drives this way.

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Is there a way to securely erase an SSD without physically destroying it?  I have read that encrypting doesn't work nor does writing over with zeros.   :(

It is correct that encrypting does nothing, but reformatting the drive should be sufficient for everyone but a professional data retrieval type person (I.E. cyberwarfare types and hardware forensics types).  I don't think even someone like geek squad have the technology to find out what bits were on a formatted drive before it was formatted, especially if you use the long form formatting (whatever that's called in Mac/Apple-land).

 

Alternatively, you could just buy them a new SSD -- just get the same kind, and let them put the OS back on.

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do this from the command line:

 

diskutil randomDisk 2 /dev/diskN

 

That should be thorough enough that even commercial tools won't get at the data. 

 

Encryption would work fine if you started with it on.  The reason it doesn't help in this case is the same reason overwriting is a pain.  SSDs don't like to overwrite the data, they just write to new locations and change the pointer.

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do this from the command line:

 

diskutil randomDisk 2 /dev/diskN

 

That should be thorough enough that even commercial tools won't get at the data. 

 

Encryption would work fine if you started with it on.  The reason it doesn't help in this case is the same reason overwriting is a pain.  SSDs don't like to overwrite the data, they just write to new locations and change the pointer.

 

 

Why would writing over the drive twice work if writing over it once didn't?  Just curious. 

 

I think I made him encrypt the drive when he first got it.  If this is true, I assume it would be difficult for someone to recover the data (well, except his password is pretty easy for a computer to guess probably - would it help for me to change his main password?).

Edited by shellylh
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It's not very hard to get at the SSD.  Unfortunately, it's not a standard SSD that I can buy at amazon and put back in.  I suppose apple would charge me a lot to replace it.   :(

 

https://www.ifixit.com/Guide/MacBook+Pro+13-Inch+Retina+Display+Mid+2014+SSD+Replacement/27849

 

Damn, even from ifixit, they are charging $314.95 for a new replacement drive. 

 

Edit:  I guess Dusty already pointed this out. 

Edited by shellylh
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Why would writing over the drive twice work if writing over it once didn't?  Just curious. 

I am curious about this myself.  I always thought it was a hysteresis thing.  Hysteresis, is a tendency for magnetic media to retain a recording.  If you write over it once, and you know the nature of the media, you can figure out if there was a 1 or a zero underneath it based on small deviations from the value it should have been if there was never any data there to begin with.  This gets shrunk dramatically the second time, and now instead of two possible values around a known constant, you have two possible values around two possible values.  It just gets fuzzier after that.

 

Those values by the way, are pretty darn small to begin with -- one requires extremely sensitive equipment to perform data forensics.

 

And yes, they don't write constant values on any drives any more, they write patterns when they're reformatting, because it makes for a better hard disk anyway.  "Like new."

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I'm thinking of updating the OS on my early 2009 Mac Mini (2.26 Intel Core 2 Duo).  I just use it as a music server for my headphone setup.  I have Snow Leopard still on it but I can't run Tidal with SL.  Would it be stupid to update to El Capitan (lots of speed increases over Yosemite I have read) or should I just install Mountain Lion on it? 

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