Epson 10020 - Manual (Page 198)

Destructive surface analysis tests a formatted hard disk for
bad tracks and updates the bad track table. Because this
option writes and reads data on the disk, it destroys all data
on any track that produces an error. You cannot run the
Destructive surface analysis on a disk that has never been
formatted.
Non-destructive surface analysis checks a formatted hard
disk for unflagged bad tracks without destroying data. You
cannot run the Non-destructive surface analysis on a disk
that has never been formatted.
The type of format you choose depends on whether you are
reformatting a disk that has been used or formatting a new disk
for the first time. (See the recommendations below.)
Reformatting a Used Disk
If you are reformatting a disk you have been using that appears
to be damaged, follow these steps:
1. Use the Non-destructive surface analysis test to check for
unflagged bad tracks.
2. If errors occur during the 000000000000Non-desctructive analysis, use
BACKUP to back up the data on your disk.
3. Run the Conditional format.
4. Run the Destructive surface analysis.
Physically-Formatting a Hard Disk E-3