A Microsoft Windows NT and Windows 2000 command that can be used to convert a file allocation table (FAT) volume to an NTFS file system without loss of data on the volume. This conversion is one-way—you cannot convert an NTFS volume to a FAT volume using this command.
The convert command cannot be used to convert the current drive. If you attempt to convert the system partition, convert is unable to lock the drive and instead schedules conversion to occur at the next reboot.
convert d: /fs:ntfs //converts D drive to NTFS.
For the full syntax of this command, type convert/? at the command prompt.
Always back up a FAT volume prior to converting it to NTFS.