Do not use any third-party MS-DOS-based disk program to repair or defragment a FAT volume used by Windows NT unless the disk program has been certified as being compatible with Windows NT version 3.5 or later. While instances of third-party utilities corrupting FAT volumes are relatively rare, some problems have occurred. Using non-Windows NT utilities are simply not worth the risk of losing an entire volume. Even the MS-DOS-based program Defrag might not work correctly if you have long filenames in the FAT volume.
You can use the Windows NT command prompt program Chkdsk to scan and repair FAT and NTFS volumes. This program incorporates all of the functionality of the MS-DOS-based Chkdsk and Scandisk utilities, including a surface scan. To do a surface scan, use chkdsk /r.
There is a Windows NT-based program available that can defragment both FAT and NTFS volumes. Microsoft has a directory that contains information about hardware and software programs that are available for Windows NT, including defragmentation utilities. This directory is called InfoSource. For information about InfoSource, see http://www.microsoft.com/infosource.
Disk media verification can be done with the SCSI utilities that ship with most SCSI controllers. Consult the documentation accompanying your hardware or contact your hardware vendor for information on verification of disk media. It is always a good idea to do a complete backup of the disk before starting a procedure of this type.