SSD, does data linger like a HDD?

Quick question regarding SSD's. When you format an SSD or delete a file, can it be recovered like data on HDDs? I am wondering how they compare security-wise to HDDs. How secure are SSDs? Any way to permanently delete SSD data so it is impossible to recover? Will impossible ever be possible?

 

Technically, it is possible to undelete data from an SSD.

To permanently delete it, you can run either a TRIM function, or just write to it a bunch of times.

I am unaware of the success rate of undeletes versus a mechanical drive though. I would assume an SSD's successful undelete rate is far lower than on a mechanical harddrive.

 

Most drives use wear leveling techniques (actually, any sensible SSD does) so there is no guarantee where a logical block will actually be in an SSD. That means that even if you try looking in the same spot for data, that spot might have moved on the SSD. No way to recover from that.

If you have a drive with garbage collection or TRIM support, it is also highly unlikely you'll be able to recover deleted data.

Bottom line: it might be possible, but there are a whole lot of technical aspects of the design that make it highly unlikely for recovery to be possible.

 

Ah good. I was gonna type out a layman's explanation of wear leveling. I sat there and thought, "OK, where should I start..."

You seemed to summed it up well in just two sentences. Thanks for saving me from my own bumbling language.