SUMMARY
Problem:
When I attempt an UNFORMAT command on a low density disk by typing
then I get the error message:
Bad sector being bypassed.
This message is displayed continuously and system seems to be hung.
Response:
This problem can occur in two situations:
• A low density disk is already formatted as low density and is then
reformatted for high density in a high density drive. When an
UNFORMAT command is attempted on this newly formatted disk, the
screen will display the error message "Bad sectors being bypassed."
This message is displayed continuously for more than 15 minutes, and
then it returns the error message:
Unable to find the MIRROR control file. If you want to search
for the MIRROR image file through the entire hard drive, press
Y, or press N to cancel the UNFORMAT command.
During these 15 minutes, the system seems to be hung.
To Reproduce the Problem
• Use the FORMAT command to format a low density disk as a low
density. For example:
C:\>format a:/f:360
-or-
C:\>format a:/f:720
• Reformat the disk as a high density disk. This requires a high
density drive and no extra parameters with the FORMAT command.
For example:
Format will display the error message:
Existing format differs from that specified.
This disk cannot be unformatted.
Proceed with Format? (y/n)
• Press Y and press ENTER to continue formatting.
• Unformat the newly formatted disk using the UNFORMAT command.
For example:
C:\>unformat a:
• A low density disk is formatted as high density in a high density
drive, and an UNFORMAT command is attempted on this newly formatted
disk.
To Reproduce the Problem
• Use the FORMAT command to format a low density disk as a high
density. This requires a high density drive and no extra
parameters with the FORMAT command. For example:
• Unformat the newly formatted disk using UNFORMAT command. For
example:
In most cases, the low density disk can be formatted successfully to
high density. But the format may not be reliable, and it will mark
many sectors as bad. For this reason, only high density disks be
formatted as high density. When an UNFORMAT command is attempted on
this disk, it has to make an attempt to read the sectors and bypass
the bad sectors.
The FORMAT command in MS-DOS version 5.0 examines if the disk is
already formatted. If the new format specified is different from the
existing format, it warns you that the disk cannot be unformatted. If
you decide to continue with formatting, the disk will be formatted for
the specified media type and the disk cannot be unformatted.