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I have the late 2010 MacBook Air and need a way to do a factory reset on it. Maybe factory reset is the wrong phrase, but I would like to delete all of the information from it so that nobody could access any of my information.

Any idea on how this can be done? (I do not have a Mac OS X disk.)

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Since SSD have spare capacity you can't really "fill them up with garbage" to overwrite all the memory cells - but two or three random write passes has been shown to reduce the amount of data that's retrievable to something like < 10% –  bmike May 11 '11 at 16:30
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3 Answers

up vote 7 down vote accepted

The Macbook Air should have shipped with a small USB drive that contains the installation software.

It won't be easy to do what you want to without booting from something other than the System disk in your Mac.

Assuming you have the USB drive that shipped with the Macbook Air (you should have unless there is a good reason why you don't have it), you should insert it and boot from it, by holding the option (alt) key just after you hear the chime when turning the machine on.

After holding the option key for a short while, you will be presented with a choice of boot volumes, one of which should be the OS X installer.

Run the installer and follow the instructions to reinstall the OS, at which point you should be given the option to wipe the current install and start fresh.

If you want extra security, you can use the Disk Utility while in the installation mode, by choosing it from the Utilities menu that is at the top of the screen.

From there you can erase the disk, choosing from a range of security options when doing so.

If you don't have the USB drive you will have to obtain one somehow - which may mean taking the Mac to an Apple Store.

Failing that, maybe you'll be able to acquire a install disk image from some place on the web and install it to an external drive that you can boot from. Not going to help with that though.

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I actually just realized that I do have that small flash drive. It is just so incredibly small and hidden in the instruction booklet. :| Thanks! –  Flipper May 12 '11 at 4:03
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It's easy to re-install the operating system. It's a free service at most Apple retail stores and you can always re-order the install media from apple if you lost it.

As to preventing someone from reading the data - that's normally done after the clean erase install. You can use disk utility and a test account to write random data over the free space once or twice to make it nearly impossible to get anything back. I haven't seen a credible source show that modern drives are any more secure after one or two passes (as compared to older technology where NSA/FBI expense units could still retrieve data after an erase attempt.)

SSD are a bit more tricky with wear leveling and extra space hidden from the OS - but unless you are worried someone will take the flash storage apart to retrieve this "hidden data" - the same two passes is shown to erase 85% of the blocks or more which for most people is enough.

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Apologies if my answer is not applicable to your MBA as I have an late '11 MBA.

But for my MBA, the above answers would be incorrect. Actually, they're technically worse than incorrect but it's not that important. To properly 'erase' all data from an SSD, you need to boot into a Linux distribution from an external drive (USB or SD or CD), open a Terminal and get to root however you prefer - I use:

$ sudo su -

but if you boot using partedmagic.com (which I think is your best option), you will be automatically logged in as root when you open a Terminal.

# hdparm -I /dev/sda

This is to determine if your SSD is "locked" and it likely would be; at which point things will either be difficult or very easy. If it's locked, see below. If it's not locked, it's easy:

# hdparm --user-master u --security-set-pass Eide /dev/sda

(this is to 'lock' your drive for the ATA Secure Erase command, the "Eide" password can be another password of your choosing)

# hdparm --user-master u --security-erase Eide /dev/sda

Though for the life of me I cannot understand the difference between "Secure Erase" and "Enhanced Secure Erase" (especially as they are both completed in mere seconds (with Enhanced actually slightly faster, but I'm sure that's not the reason it's 'more' Secure than Secure (go figure), what I do is - quite simply - to do both:

# hdparm --user-master u --security-set-pass Eide /dev/sda

# hdparm --user-master u --security-erase-enhanced Eide /dev/sda

You can add --verbose to all of those to get more information, but I'd be lying if I claimed to have a clue about the output ;)


Now if your SSD is locked (and I imagine it will be), you have to get it unlocked somehow which is so much more complicated than it should be. Your best bet is to download Parted Magic and click Start > System > Erase and it will open a GUI menu showing your available drives, select your SSD hard drive, confirm the next screen, and then it will offer you the option to put the drive 'to sleep' - which is easy to do on any system but OS X. With OS X there is no guarantee but this thread is probably the best list of options you can try if simply closing your lid for a couple minutes then opening it doesn't put your drive to sleep or if the Parted Magic option to 'sleep' your drive doesn't allow you to boot back into the saved state.

Hope this helps. FWIW the answers above, whilst no doubt well-intentioned, are absolutely incorrect (as you'll quickly discover reading the MacRumours thread above - or even Googling basic SSD facts using search terms like "SSD ATA Secure Erase" etc). gl gl

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While this may be technically correct, it's overkill for most users. –  jaberg Feb 22 '12 at 13:53
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