So unlike for HDs, this is not a good way to make sure your data is gone, and cannot be read by someone else.Īll of those commands are 'bad' for the SSD in the sense that any writes use up the limited number of writes an SSD has, decreasing the lifetime of the SSD. So any of the commands you can use to 'overwrite' a file ( cp, dd, cat, shred, and many more) have this weakness: It does not actually overwrite the file at all, instead it writes zeroes, random data or whatever to new blocks. So instead of erasing and overwriting the same block, wear leveling will make the SSD pick a different, unused block, and will write to this block, leaving the data on the old block in place.Īnd if the data on the old block is in place, that means it still can be read.

But erasing is an operation that can only be executed a limited number of times each time you do an erase, you 'weaken' the hardware, until the block cannot be properly erased anymore. To write a block to an SSD, you need to erase it first, and then you can write the new data. That's because all recent SSDs use something called 'wear leveling'. Writing a block to an SSD does not overwrite the old block.

Ata secure erase