That won't overwrite pages not allocated to a namespace (which can happen due to wear levelling/underprovisioning, or because the controller has decided to stop using that page because it's unhealthy).
Flash looks like a simple array of blocks, but under the hood there is a controller that allocates writes to different pages. You need to tell the controller to erase all pages if you want to guarantee data destruction.
Flash looks like a simple array of blocks, but under the hood there is a controller that allocates writes to different pages. You need to tell the controller to erase all pages if you want to guarantee data destruction.