Whether you choose to erase data from the drive or to wipe data from unoccupied drive space, the methods of overwriting over these spaces are the same.
When using One Pass Zeros, the number of passes is fixed and cannot be changed. When the write head passes through a sector, it writes only zeros (0x00 characters).
When using One Pass Random, the number of passes is fixed and cannot be changed. When the write head passes through a sector, it writes series of random characters.
You indicate the number of times the write head passes over each sector. Each overwriting pass is performed with a buffer containing the pattern you specified (ASCII string).
The write head passes over each sector three times. The first time is with zeros (0x00), the second time with 0xFF and the third time with random characters. There is one final pass to verify random characters by reading.
The write head passes over each sector seven times (0x00, 0xFF, Random, 0x96, 0x00, 0xFF, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector seven times (Random, Random, 0x00). There is one final pass to verify zeros by reading.
The write head passes over each sector seven times (0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector three times (0xFF, 0x00, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector seven times . (0x00, 0xFF, 0x00, 0xFF, 0x00, 0xFF, 0xAA). There is one final pass to verify random characters by reading.
The write head passes over each sector two times. (0x00, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector three times. The first time with 0xFF, second time with zeros (0x00) and the third time with random characters. There is one final pass to verify random characters by reading.
The write head passes over each sector three times. The first time with random characters, second time with zeros (0x00) and the third time with 0xFF. There is one final pass to verify random characters by reading.
Baseline method overwrites disk's surface with just zeros (0x00).
There is one final pass to verify random characters by reading.
Enhanced method - the write head passes over each sector three times. The first time with zeros (0x00), second time with 0xFF and the third time with random characters.
RL method - the write head passes over each sector three times (0x01, 0x27FFFFFF, Random).
MFM method - the write head passes over each sector three times (0x01, 0x7FFFFFFF, Random).
The write head passes over each sector three times (0x00, 0xFF, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector two times (Random, Random). There is one final pass to verify random characters by reading.
The write head passes over each sector seven times (0xFF, 0x00, Random, Random, Random, Random, Random). There is one final pass to verify random characters by reading.
1. The write head passes over each sector one time (0x00).
2. The write head passes over each sector one time (Random).
3. The write head passes over each sector three times (0x00, 0xFF, Random).
The write head passes over each sector once with random characters. There is one final pass to verify random characters by reading.