Preparing Mac Air for Sale

[Bigredhunk]

...but before... I recommend a full disk encryption with FileVault and then... do the Cmd+R to re-install. This will prevent next owner finding those files you wouldnd't want anyone to see

I apologize for bumping such an old thread. I'm in the middle of prepping my MBA for sale, and am getting ready to wipe it.

I'm going through the "What to do before selling or giving away your Mac" instructions found here:

http://support.apple.com/en-us/HT201065

1) Deauthorized computer from iTunes.
2) Backed up data to external hard drive.
3) Unchecked the "Find My Mac" box in iCloud settings
4) Signed out of iCloud
5) Signed out of iMessage

So I'm now at the reformat hard drive and reinstall OSX (Lion, in this case). When I go into my Security & Privacy settings, it shows that Filevault is turned on for this computer. I didn't just turn it on, it's been on apparently. So to do a full disk encryption with Filevault (as is written above), I don't have to do anything, right? It's already been done, as I've had Filevault running to this point? I just want to make sure that's correct.

Thank you!

edit

I just wanted to check this as well. On the Apple forums, a member asked the question:

Is it possible to completely remove ALL data when wiping?? Is ALL data completely wiped and irretrievable from my old mac once this process is done? I have heard of others illegally retrieving data from old discarded hard drives previous owners had 'wiped' clear.

The response was:

When you erase a drive, you can do it fast/non-secure or slow/secure. Choose the "secure" method and specify 1, 3 or 7-pass option. For large disk drives this can take a VERY VERY LONG TIME. But if you want to be safe, what's a day or two.

The multiple-pass secure options writes different bit-patterns to the drive, before it finally erases it with all zeros, which leaves nothing for anyone to recover later on.

If you choose the unsecure method (the default) it only initializes the information that says how many files are on the drive and where to start writing when new files are created. The actual part of the disk that had your old data is not even touched, so with the right kind of software that information is able to be recovered to varying degrees of success.

The 3-pass secure erase method is what the DOD (Department of Defense) recommends for erasure of drives.

See this for a lot more information about securely erasing disks:

http://www.it.cornell.edu/security/depth/practices/media_destruct.cfm

have fun.....

Is this something about which I should worry or does Filevault basically take care of this for me?

Thanks again.

 

[motrek]

Do not do a secure erase on an SSD. That information is out of date and should be updated.

A secure erase on an SSD will only put wear on it and isn't guaranteed to overwrite all your data.

If you had FileVault turned on before you put your data on the computer, then you're safe. No need to secure erase anything--any data recovered will be encrypted using your old FileVault key which the new owner won't know.

Otherwise, I think a good way to effectively erase the data on an SSD is to copy a large file to it, like a movie. Then you can duplicate (copy and paste) the file until the drive is more or less full. That should overwrite whatever you had on there before and then you can just delete all those big files.