The verification process happens after the last erasure pass is done writing, unless the method otherwise states. It will check the hard drive if all* sectors have the correct data** in it.
The software will overwrite all old data but this has to be confirmed. Therefor there is a verification process. NIST guidelines advise at least 25% verification. But how higher the verification is set the more secure the erasure is done. We will advise 100% verification.
You can fail the process if a dirty/bad sector and/or errors are found.
If you need help from our support team, please email us at email@example.com
*= you can set the amount of sectors that need to be checked from 2% to 100%.
We advise to go for 100% to be full secure. If you need more information on the verification levels please contact us.
**= the correct data is the data that has to be written to the hard drive as set to that specific pattern.