I plan to sell my Macbook Air 2011 with lion. I used the disk utility nonsecure erase disk function which only took a couple seconds to erase the disk and then reinstalled lion via internet recovery. My question is, if I sell this to someone, can they easily recover the data from my harddrive which was erased using non secure erase?
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Erasing MacBook Air
- Thread starter teknobrat2003
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Short answer: yes. The data isn't erased. If you want to erase it you need to do a secure erase - though I'm not sure how effective that is on an SSD. I was always told SSDs could choose to write data to different areas than specified for wear leveling.
Theoretically yes. But some SSDs do their own housekeeping which makes it very bad to recover existing data. But Apple's own disk utility prevents secure erasing on the Apple SSDs so you don't have much choice in this.
2011 refurb bought a couple weeks ago, came with Lion. Used it for a couple days and wiped it to reinstall. Wiped it from the recovery mode, 1 pass secure wipe.
If you select the drive from the tool, it's grayed out. If you select the partition, secure erase is available. Just double checked since you had me second guessing myself
If you select the drive from the tool, it's grayed out. If you select the partition, secure erase is available. Just double checked since you had me second guessing myself
I'm not sure if it even helps with an SSD anyways, since they can choose to write data wherever they want for wear leveling. I just figured I'd try it since I never thought an SSD could be secure erased.
Here is a kb about it:
http://support.apple.com/kb/HT3294
Quote: "Note: With OS X Lion and an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. These options are not needed for SSD because a standard erase makes it difficult to recover data from an SSD."
http://support.apple.com/kb/HT3294
Quote: "Note: With OS X Lion and an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. These options are not needed for SSD because a standard erase makes it difficult to recover data from an SSD."
What I've heard is that if the data was encrypted when it was first written (i.e. if you have FileVault2 active), that if you format the drive it would be very difficult for someone to recover data. If it is unencrypted, then it could be recovered a bit more easily from an SSD than a HDD since traditional wiping techniques don't work on SSDs.
This is the correct answer. Encrypt with Filevault2 before you start using the drive. Everything else with an SSD is a guess.
I agree with the FileVault comments but for what it is worth I thought I would make the following comments relating to OSX Secure Erase options on SSDs
Mac users without SSDs keep suggesting SSD users (MBA for example) can secure erase via Disk Utilities or via Disk Utilities through the Recovery partition. You can't do that if you have the newer Macs. The option is greyed out. But there are easy ways to get around it. I should note though that secure erase through Disk Utility doesn't work properly on SSDs as it does on non-SSD drives. Google this and also see notes above. The whole issue of securely erasing SSD's and TRIM and Garbage Collection and the efficacy of overwriting is beyond my points I wish to make here, but is clearly a factor(if not the key factor) in the whole process.But anyway here's how you use OSX Secure Erase on SSDs if you really want to.
Option 1: You need a Recovery Partition USB Drive. It is like the current Recovery Partition on new Macs but it is on a thumb drive. Apple support has instructions or Google it. You boot into the RP thumb drive by pressing the Option key after start. Then in Disk Utility you format the SSD drive as Journaled Encrypted. Once it is formatted in this form you can then securely erase the free space which is the entire drive as you have just formatted it.
Option 2: Same as above up to the point you see the Disk Utility, Time Machine etc etc option screen. Launch Terminal from the Utilities Menu then use the "diskutil" command.
Enter "diskutil list" to find the disk/volume you want to erase (e.g. disk0 or disk0s2)
Enter "diskutil secureErase" to see the erase strength options.
Once you know what you want to do, as an example enter "diskutil secureErase 4 disk0" to erase the complete SSD drive of a MacBook Air to US DoE 3-pass standard.
It takes about 1.5 hours to do a three pass.
Does this fully Secure Erase an SSD? No. But it is better than nothing.
Just encrypt your drive to begin with.
Also you will need to do a full OSX install (or download if you have the newer Macs). I think you can erase freespace using diskutil but I have never tried this option.
Final note, I provide this info, not because it is a true secure erase of an SSD, but because so many people say you can just choose secure erase freespace or the drive when this is not true on the new Macs with SSDs!!! Apple has greyed the option out in the GUI format of Disk Utilites so you can only do it through the Terminal or if the drive is formatted HFS+ Encrypted.
Silver
Mac users without SSDs keep suggesting SSD users (MBA for example) can secure erase via Disk Utilities or via Disk Utilities through the Recovery partition. You can't do that if you have the newer Macs. The option is greyed out. But there are easy ways to get around it. I should note though that secure erase through Disk Utility doesn't work properly on SSDs as it does on non-SSD drives. Google this and also see notes above. The whole issue of securely erasing SSD's and TRIM and Garbage Collection and the efficacy of overwriting is beyond my points I wish to make here, but is clearly a factor(if not the key factor) in the whole process.But anyway here's how you use OSX Secure Erase on SSDs if you really want to.
Option 1: You need a Recovery Partition USB Drive. It is like the current Recovery Partition on new Macs but it is on a thumb drive. Apple support has instructions or Google it. You boot into the RP thumb drive by pressing the Option key after start. Then in Disk Utility you format the SSD drive as Journaled Encrypted. Once it is formatted in this form you can then securely erase the free space which is the entire drive as you have just formatted it.
Option 2: Same as above up to the point you see the Disk Utility, Time Machine etc etc option screen. Launch Terminal from the Utilities Menu then use the "diskutil" command.
Enter "diskutil list" to find the disk/volume you want to erase (e.g. disk0 or disk0s2)
Enter "diskutil secureErase" to see the erase strength options.
Once you know what you want to do, as an example enter "diskutil secureErase 4 disk0" to erase the complete SSD drive of a MacBook Air to US DoE 3-pass standard.
It takes about 1.5 hours to do a three pass.
Does this fully Secure Erase an SSD? No. But it is better than nothing.
Just encrypt your drive to begin with.
Also you will need to do a full OSX install (or download if you have the newer Macs). I think you can erase freespace using diskutil but I have never tried this option.
Final note, I provide this info, not because it is a true secure erase of an SSD, but because so many people say you can just choose secure erase freespace or the drive when this is not true on the new Macs with SSDs!!! Apple has greyed the option out in the GUI format of Disk Utilites so you can only do it through the Terminal or if the drive is formatted HFS+ Encrypted.
Silver
The best solution is to turn on FileVault2. Then you can reboot and erase the data. It may not be perfect, but it increases the odds that someone would be unable to recover old data.
I just encrypt the drive using FileVault (that takes awhile too). Once it completes, I do a standard install, performing a simple erase first. I would avoid any attempt to perform a multi pass secure erase on a SSD which might affect the performance for the new owner.
