First, it's not good for the drive, and second, it wouldn't work properly anyway. Not good for the drive because it writes to the drive too many times. Wouldn't work properly because just like OSX cannot control where it writes to on the drive. The SSD's controller is responsible for that, and due to wear leveling algorithms, wouldn't get you the intended results. With an Apple SSD, all you need is to perform a "erase." Third party SSD drive you would have to perform a "secure erase."
http://www.ocztechnologyforum.com/forum/showthread.php?75832-SSDs-A-Look-Inside&nand+transistor
NAND flash memory uses floating gate MOSFET transistors. Their default state is when the charge is over the 50%. If the flow through the gate is above the 50% threshold, it has a value of 1. When the charge passing through drops below the 50% threshold, the value changes to 0.
0's are data, 1's is erase....the fundamental laws of MLC NAND dictate this. You only write the 0's when you write data to NAND.
So in an erased state the NAND has to report a 1.
This is how it is done on a disk drive or 'HD'.
https://docs.google.com/viewer?url=http://cmrr.ucsd.edu/people/Hughes/DataSanitizationTutorial.pdf
Most modern SSDs have built-in commands that instruct on-board firmware to run a standard sanitization protocol on the drive to remove all data. Since the manufacturer has "full knowledge" of the drive's design, these techniques are reliable, fast and effective, and take all of two minutes.
ATA Secure Erase is part of the ATA ANSI specification and when implemented correctly, wipes the entire contents of a drive at the hardware level instead of through software tools. Software tools over-write data on hard drives and SSDs, often through multiple passes; the problem with SSDs is that such software over-writing tools cannot access all the storage areas on an SSD, leaving behind blocks of data in the service regions of the drive (examples: Bad Blocks, Wear-Leveling Blocks, etc.)
When an ATA Secure Erase (SE) command is issued against a SSD’s built-in controller that properly supports it, the SSD controller resets all its storage cells as empty (releasing stored electrons) - thus restoring the SSD to factory default settings and write performance. When properly implemented, SE will process all storage regions including the protected service regions of the media.
Secure Erase is recognized by the U.S. National Institute for Standards and Technology (NIST), as an effective and secure way to meet legal data sanitization requirements against attacks up to laboratory level.
On OSX there is not way to secure erase at a software level a SSD drive. But I was explained by Apple Business that Apple's firmware on the drive has 'hardware level ' encryption on the drive itself. When you initiate a 'erase' function it activates the firmware to first encrypt and then secure erase the drive.
Secure Erase issues Apple's SSD controller firmware's pre-programed ATA Securiy Erase Unit command. It applies a voltage spike at a specific voltage to all of the NAND simultaneously flushing the stored electrons from the flash memory cells, thus cleaning the NAND. Thus, when the Secure Erase command is ran and the voltage to all the NAND is over 50%, all the NAND is set to an erased to a unrecoverable state. speeds are reset to default, and it is in ready to be written to state.
There isn't a 'secure erase' function on a Apple OEM SSD. It is activated via firmware when it receives a 'erase' function. If you have a 3rd party SSD, M4, Samsung 830, you will have to hook it up to windows if you want to ensure to secure erase that SSD. I don't think OSX will activate a 'firmware secure erase' or 'hardware' erase as OSX doesn't have to 'language' to activate that function on 3rd party SSD drives if it exists on those drives in the first place. I don't know about that but I am sure most do. Which one's do or do not I am not sure.
This reason and Trim support are the main reasons I stick with a Apple OEM SSD drive, slower or not. In everyday use you cannot tell the difference between the drive I am using( Apple SSD Toshiba HG3 GBSJ model) and a 6G drive in every day use.
I run my business and this function is a must for me.
This sofwware "PMagic' does the same thing as Apple's SSD's firmware on Windows.
http://howto.cnet.com/8301-11310_39-20115106-285/how-to-securely-erase-an-ssd-drive/
