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I have a late 2011 MacBook Air with an SSD and Lion. I used it for a while and then I activated File Vault 2. Now the data is encrypted, but I need to securely erase it so I can sell the computer.

I thought about erasing it with gparted by installing it on a USB.

Any suggestions?

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It's my understanding after a TRIM command, there is no real way to still recover deleted data from an SSD drive. –  Gerry Jun 18 '12 at 8:48
    
What do u means Gerry? so after deleted it's yet secure? –  James Jun 20 '12 at 22:28
    
For link purposes: How to securely erase an SSD drive? (2011-08-19) –  Graham Perrin Dec 9 '12 at 0:41
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7 Answers 7

up vote 12 down vote accepted

If you have a USB Flash Drive of 8 GB of size, you can make a Lion Installer and use it to securely erase the Drive.

http://macintoshhowto.com/osx/how-to-make-an-os-x-lion-usb-thumb-drive.html

You can also make a USB Bootable Recovery Disk as explained here by Apple:

http://support.apple.com/kb/DL1433

Once you have done either you can hold down the OPTION key while restarting your computer and booting from it.

When it loads up, it will give you a few different options, you will need to use the Disk Utility part and highlight your HD and choose the Erase Tab. Under the erase settings will be a security option when you can write the disk to 0 once or even multiple times.

There is a guide on it here:

https://discussions.apple.com/docs/DOC-3251

See the part where it says

How to Zero erase and install OS X

I hope that helps you out.

Updated

The guy at the bottom of this post:

http://forums.macrumors.com/showthread.php?t=1267158

points out a work around to securely erase the SSD drive in the MacBook Air through encryption.

This is what he says:

cmace127

I found a workaround. Restart the computer and hold option to enter the setup screen. Go into disk utility and select the drive. Erase the drive using "Mac OS Extended (Case-sensitive, Journaled, Encrypted). Make a password for the encryption, it doesn't matter what it is because you won't need it. Hit "Erase". Now select the volume and the "Erase Free Space" and "Security Options" buttons should no longer be grayed out. Click and select your level of security and off you go. I presume "Erase Free Space" and "Security Options" should do the same thing because you just erased the drive so all space is considered free. This worked for me so let me know if it helps.

Let me know if that's works, this should securely erase the drive since it will then be encrypted.

Also, in the future with lion be sure to use File Vault 2 so that you don't have to worry about this again.

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yes, that's it,thanks and how much secure is it? –  James Jun 19 '12 at 0:14
    
@james I updated my answer to be more helpful with some information I found. –  de_an777 Jun 19 '12 at 2:13
    
ok thanks i will try this procedure next week and i will inform here if it's ok. thanks!! –  James Jun 19 '12 at 13:16
    
and how much secure is this procedure? the controller will really erase each sector on ssd?. thanks! –  James Jun 20 '12 at 9:08
    
@james Technically yes, once the drive is encrypted, you'll be able to erase the drive with the security options, and it can pass over up to, if I remember correctly, 35 times. That should securely erase everything. The drive should be really really blank now. You could even do that again if you want, just don't wear out the SSD too much if you don't have to. –  de_an777 Jun 20 '12 at 12:51
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Its looks like securely erasing an SSD is a different chore than erasing a traditional hard drive. Unconfirmed but it looks like Apple is actively disabling the legacy erase techniques for SSD drives, since they don't work as noted in Ask Ars: How can I securely erase the data from my SSD drive?

As pointed out in a recent research article, there isn't a standard method for securely deleting data from a solid state drive. Hard disk drives have had this problem solved for ages, and can execute a secure delete by filling the space occupied by an incriminating file with zeroes or multiple writes of different characters...

The overwriting procedure that works so well for HDDs doesn't work as well for SSDs for a couple of reasons. One is that many SSDs have extra storage space that's not accessible by users. This is called over-provisioning, and some deletion tools won't give you access to this area (if you can go through the BIOS and uninstall your drive, you can get full access). While the research paper noted above that overwriting did obscure all of the data in some of the SSDs they tested, some still had old readable data on them after twenty overwrites. This can happen because of firmware bugs, and unless you're able to physically confirm that this procedure works on your SSD of choice, it's not reliable enough for a real secure erase.

...

Likewise, it is almost impossible to securely delete an individual file on an SSD, because the way that SSDs write and delete files is scattered, and a user has no control over what an SSD is doing where. If that's the kind of security you're looking for, your best bet is encryption, which we will cover in a little bit.

...

Many SSDs today also come preinstalled with secure wiping utilities that are meant to actually eradicate data from cells. But of the twelve drives tested by those researchers, only four of twelve erased their data reliably, and one that claimed to be securely erasing everything was just doing the old "forget where everything is and leave it there for now" trick, and all the data was still retrievable. Some drives are known to have better erase tools than others—for instance, drives with Indilinx controllers have a "Sanitary Erase" that deletes all data and restores drives to their out-of-the box condition.

Your best bet going foward is to use encryption and then throw away the encryption key to "securly erase" it. So going forward if you are concerned with security and your using SSD, you may want to enable FileVault2 immediately before you start putting data on the SSD. Unfortunately for data thats already on the drive it may be extremely difficult to securely delete it, depending on the SSD used in the MacBook Air. There maybe re a reset tool for the SSD from the manufacture, but seeing how its an Apple OEM specific part from a 3rd party vendor its probably going to be unlikely to exist.

If security is an issue you may want to hang onto the SSD or destroy the SDD to be the most secure.

If your MacBook Air supports Lion Recovery Mode, and your using full disk encryption such as FileValut2 you will not need anything else to do it other than follow the steps below.

  1. Boot your MacBook Air into Recovery Mode by holding down Command+R while booting it.

  2. Open the Disk Utility Program, select the drive you want to securly erase.

  3. Select the "Erase" tab

  4. Click "Security Options..."

  5. Drag the slider to the Most Secure setting or some where in between and then select "OK"

  6. Then click "Erase..." and follow the remaining on screen prompts.

Note: For more information on how secure the Disk Utilities Secure Erase feature is see About Disk Utility's erase free space feature

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this procedure show me grey button and even if how much secure it is? thanks –  James Jun 20 '12 at 9:42
    
Which button is grey? –  MrDaniel Jun 20 '12 at 14:47
    
security options –  James Jun 20 '12 at 22:29
    
If you encrypt the disk first it's not greyed out anymore -- just not sure if it's "safe" to do (SSD damage?). –  Tuinslak Apr 12 at 19:17
    
It may be the case that Apple is accounting better for SSDs now a days. It be the case that since it's encrypted it does not really do anything more when you tell it to secure erase it, its an unlink and done kind of thing. If you have a spare drive see what it does if it sits there for hours erasing, that's bad. Almost instant its probably doing like I said... –  MrDaniel Apr 13 at 20:57
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You can do this by booting into the Recovery partition, launch Terminal from the Utilities menu and use the diskutil command.

Enter diskutil secureErase or man diskutil for some explanation how erasing with diskutil works. To find the diskidentifier of the volume you want to erase (for instance disk0s2), enter diskutil list.

The following example will erase a volume with US DoE 3-pass secure erase:

diskutil secureErase 4 disk0s2

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If you're on Lion, odds are you have the new recovery partition installed.

What you can do to erase your hard-drive is to boot into the Recovery partition by holding down command-R when you start your notebook.

This will boot your computer into a limited mode, where you will be able to access Disk Utility. From there, select the partition you want to erase, and then Erase it. Select Security Options... to make the erase complete and secure, so that the data won't be accessible again.

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thanks for your answer, did u do this process? i tried but security option seems gray, how i can unblock them? btw are u sure it's secure? i read some post here and there about unsecure wipe ssd is. thanks! –  James Jun 17 '12 at 23:18
    
@James: are you sure you launched it from the Recovery partition? If it's still gray, try unmounting the HD first (from a Terminal). Also, I'm not completely sure about whether this is 100% effective for SSDs, maybe this article -- arstechnica.com/security/2011/03/… -- can help. –  houbysoft Jun 17 '12 at 23:34
    
yes, infact i can initialize it but not with security option enabled :( I did after reboot so i'm sure it's unmounted, if not i think i can't initialize it. thanks for your suggest (link) but it just say as solution: encrypt, ok but i did it but only after some times i used it unencrypted. so i don't want the files in that period are recoverable. i don't know if it's clear, i hope…so any suggestion to solve this? –  James Jun 17 '12 at 23:47
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You cannot securely erase SSDs this way. –  Gerry Jun 18 '12 at 8:23
    
it's so strange apple did give us some kind of method to erase secure ssd, it can't believeble. what about gparted, do u think it's secure? –  James Jun 18 '12 at 9:28
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If you boot from an external drive or recovery mode it is also sufficient to zero the internal disk if it's an SSD. One pass is enough. Use Disk Utility to discover what device the internal disk uses (probably /dev/disk0). If you see a partition like /dev/disk0s2 then the disk is /dev/disk0). Use "Get Info" to find out the mount point.

Then quit Disk Utility and load the Terminal and do:

diskutil zeroDisk /dev/disk0

Afterwards it will be necessary to repartition and format the disk, which you can do from Disk Utility or the command line.

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So you mean if you format the drive, someone may use the recovery software to see your data?

Just delete the files you don't want anyone to see then copy dummy data until the disk is full, delete the dummy data, and your previous data is completely gone.

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so it's the same as make a 7pass secure formatting in utility disk? –  James Jun 19 '12 at 0:16
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Go to Recovery by pressing CmdR while restarting and erase your Mac's disk in Disk Utility. Then, reinstall the OS.

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