We are all more than ever aware of the need to securely delete sensitive files and to sanitise disks before selling on a computer. It seems, though, that SSDs may need a bit more case because, according to the Non-Volatile Systems Laboratory of the University of California San Diego, "naïvely applying techniques designed for sanitising hard drives on SSDs, such as overwriting and using built-in secure erase commands is unreliable and sometimes results in all the data remaining intact."
The research students (Laura Grupp and Michael Wei) go on to warn: "Our results also show that sanitizing single files on an SSD is much more difficult than on a traditional hard drive. We are working on designing new FTLs that correct these issues and also exploit properties of flash memory to maintain performance while sanitizing the flash drive. However, Ben Brooks, writing in The Brooks Review has a word of comfort:
"From what I can gather this is not widespread and is a result of defects on the manufacturing side – meaning this may not may not effect your SSD"
I don't know about you, but I had never considered the possibility that the traditional techniques of overwriting data could be flawed when applied to SSDs. As we come to rely more on solid-state storage it will be important to keep an eye on this research.