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hehe299792458
Sep 27, 2011, 03:08 PM
I'd like to erase the SSD in my 2011 Macbook Air before I give it to a friend. I have purchased a copy of Lion in the App Store and burned the dmg to a USB drive. I have installed Lion on other machines by this way.

However, I can't seem to get the MacBook Air boot from the USB. So, I can't get to disk utility. How do I erase the SSD?



Hellhammer
Sep 27, 2011, 03:12 PM
Have you tried holding the alt button and then selecting the Lion DMG as the boot up volume? MBA boots so quickly so it may be hard to press it at the right time, so I usually keep tapping the alt key instead of just holding it.

deeddawg
Sep 27, 2011, 03:34 PM
The Lion version in the App store is NOT suited for the 2011 Macbook Air. Different drivers or something. In time perhaps it will be, but for now the thing to do is use Lion Recovery to reformat and reload your system.

See http://support.apple.com/kb/HT4905 and http://support.apple.com/kb/HT4718

Boot holding down Command-R and be sure to have an Internet connection as you'll be pulling down about 3.5GB for a reinstall I believe.

hehe299792458
Sep 27, 2011, 03:45 PM
The Lion version in the App store is NOT suited for the 2011 Macbook Air. Different drivers or something. In time perhaps it will be, but for now the thing to do is use Lion Recovery to reformat and reload your system.

See http://support.apple.com/kb/HT4905 and http://support.apple.com/kb/HT4718

Boot holding down Command-R and be sure to have an Internet connection as you'll be pulling down about 3.5GB for a reinstall I believe.

It's fine with me if I download Lion again through the internet recovery mode. But what I need right now is to get to the disk utility on the Lion and secure erase my SSD. 7 pass, or something.

Hellhammer
Sep 27, 2011, 03:46 PM
It's fine with me if I download Lion again through the internet recovery mode. But what I need right now is to get to the disk utility on the Lion and secure erase my SSD. 7 pass, or something.

Recovery mode includes Disk Utility.

hehe299792458
Sep 27, 2011, 05:36 PM
Recovery mode includes Disk Utility.

Thanks. It does indeed have disk utility.

However, it doesn't seem to have the secure erase options. Is there any way to secure erase my SSD? With a simple reformat, data can be quite easily recovered with a lot of software.

deeddawg
Sep 27, 2011, 06:28 PM
Couple thoughts....

After all your files are deleted, copy a large data file (DVD image?) over and over to fill the SSD thereby overwriting any available blocks. Copy all files in folder A to new folder B, rename B and move it into A. Repeat. With a 2GB file, 7 or 8 iterations will fill the SSD.

Secure erasure on an SSD behaves differently than on a HDD due to wear-leveling. Also no real need to overwrite a block multiple times (and arguably it's better not to do so on an SSD).

Alternately, turn on FileVault such that the system is encrypted, then reboot / reformat / reinstall?

hehe299792458
Sep 27, 2011, 11:04 PM
Couple thoughts....

After all your files are deleted, copy a large data file (DVD image?) over and over to fill the SSD thereby overwriting any available blocks. Copy all files in folder A to new folder B, rename B and move it into A. Repeat. With a 2GB file, 7 or 8 iterations will fill the SSD.

Secure erasure on an SSD behaves differently than on a HDD due to wear-leveling. Also no real need to overwrite a block multiple times (and arguably it's better not to do so on an SSD).

Alternately, turn on FileVault such that the system is encrypted, then reboot / reformat / reinstall?

I already encrypted my data with filevault, and I filled up the SSD once with incompressible h264 files once. Is there anything else I should do to make sure that everything's gone forever?

Hellhammer
Sep 28, 2011, 01:06 AM
I already encrypted my data with filevault, and I filled up the SSD once with incompressible h264 files once. Is there anything else I should do to make sure that everything's gone forever?

Well, the only way would be to drop the SSD into a can of corrosive acid and wait for the SSD to corrode. Or break the SSD in some other way.

Otherwise you are pretty much set with what you have done, the data should be irrecoverable.