that link is a bad test. they wrote 0's to the drive, which is bad because 1) empty nand flash contains all 1's and 2) writing 1's or 0's doesn't mark the bloc

that link is a bad test. they wrote 0's to the drive, which is bad because 1) empty nand flash contains all 1's and 2) writing 1's or 0's doesn't mark the blocks as cleared, you have to use secure erase