Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have a Kingston SSDNow V+ 64GB SSD, and I understand how writing/erasing of the NAND wears out the flash.

This is because writing/erasing the NAND damages the oxide layer surrounding the floating gate, which over time leads to electron trap-up, where electrons get trapped in the oxide layer itself. This causes the difference between 0 and 1 states of the cell to slowly disappear. Dealing with this slows performance. Reference

This can be "reset" by applying larger voltage in the opposite direction of the cells to remove the electrons that block the cells.

Is there any software method that I could use to make the SSD apply the voltage to the NAND?

share|improve this question
3  
By the way, the super-technical term for this "reset" process is erasing. –  David Schwartz Apr 26 '12 at 11:23
1  
Actually, I'm now convinced my comment is incorrect. The "reset" process he is talking about would remove electrons trapped in the oxide layer, not in the floating gate. So far as I know, no flash implements such a "reset" in hardware. –  David Schwartz Apr 29 '12 at 21:35

2 Answers 2

My question is; is there a software hack that could enable said feature?

Yes, it's called TRIM, and is enabled by default on most SSDs on most modern operating systems.


As the question was edited to be more valid, and the content changed slightly, I offer here an updated answer.

There is no way to "reset" cells to remove the electrons trapped in the oxide layer. Once electrons are "trapped", they are stuck in the oxide layer (usually silicon dioxide) reducing its insulating properties. After a certain threshold, each flash cell cannot be differentiated from its 0 or 1 state, and the cell is then considered "bad".

TRIM is one technique to reduce the amount of read/write cycles required to maintain a filesystem on the drive, as is the wear-leveling algorithm present in the drive controller's firmware. Most SSDs are also over-provisioned, so your 120 GB drive actually has a few gigabytes extra, which are swapped in when a bad cell occurs.

share|improve this answer
1  
+1 for a link to an "Excellent Paper". Also available at csee.umbc.edu/~squire/images/ssd1.pdf in case Scribd requires a subscription. –  xbsd Dec 4 '13 at 13:34

SSDs are quite self-contained, not giving any outside access to the NAND. So there is no way to via software apply arbitrary voltages to the cells.

Then again, what you are suggesting is something regularly done by SSDs in course of normal operation. You erase a cell by applying a strong voltage to the opposite side from which you apply the voltage when writing to it.

From what I have read in the literature the best way to detrap the electrons in the oxide layer is rest and temperature. If you just leave the array be with no reading, writing or erasing the electrons in the oxide layer (and in the floating gate) will leak out over time. Heat speeds up this process. This is why an SSD which is not heavily used can last far longer than what the ratings suggest.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.