
                               DISKSAVE.EXE
-----------------------------------------------------------------------------

<Intel Machines Only>

DiskSave allows you to save the Master Boot Record and Boot Sector as binary image files.  Once these critical disk structures have been saved, they can be easily restored if they become corrupted later on.


Master Boot Record
-------------------
The Master Boot Record (MBR) contains code that the BIOS on x86-based computers uses to read the partition table and jump to the operating-system partition.  This sector also contains the partition tables.  If this sector becomes damaged, the machine will not boot.  Typical symptoms include hanging with a black screen immediately after the machine POST routine, or messages such as "Invalid partition table" or "Missing operating system."


Boot Sector
------------
The Boot Sector contains code that loads the operating system kernel or a multi-boot loader.  A corrupt Boot Sector can result in STOP:0x0000007B failures during boot with Windows NT.  The machine may also hang prior loading NTLDR which displays the boot selections.


Virus Issues
-------------
The most common cause of problems with the MBR or Boot Sector are viruses.  Viruses which damage these areas of the disk are operating system and file system independent.  They do their damage while the machine is booting, before the operating system is loaded.


Functions
----------

F2 - Backup the Master Boot Record
This function will prompt for a path and filename to save the MBR image to.  The path and filename are limited to 64 characters.  The resulting file will be a binary image of the sector and will be 512 bytes in size.  The MBR is always located at Cylinder 0, Side 0, Sector 1 of the boot disk.

F3 - Restore Master Boot Record
This function will prompt for a path and filename for the previously save Master Boot Record file.  The only error checking is for the file size (must be 512 bytes).  Copying and incorrect file to the MBR will permanently destroy the partition table information.  In addition, the machine will not boot without a valid MBR.  The Path/filename is limited to 64 characters.

F4 - Backup the Boot Sector
This function will prompt for a path and filename to save the Boot Sector image to.  The path and filename are limited to 64 characters.  The resulting file will be a binary image of the sector and will be 512 bytes in size.
The function opens the partition table, searches for an active partition, then jumps to the starting location of that partition.  The sector at that location is then saved under the filename the user entered.  There are no checks to determine if the sector is a valid boot sector.

F5 - Restore Boot Sector
This function will prompt for a path and filename for the previously save Boot Sector file.  The only error checking is for the file size (must be 512 bytes).  Copying and incorrect file to the Boot Sector will permanently destroy Boot Sector information.  In addition, the machine will not boot without a valid Boot Sector.  The Path/filename is limited to 64 characters.

F6 - Disable FT on the Boot Drive
This function may be useful when Windows NT will not boot from a mirrored system drive.  The function looks for the bootable (marked active) partition.  It then checks to see if the SystemType byte has the high bit set.  Windows NT sets the high bit of the SystemType byte if the partition is a member of a Fault Tolerant set.  Disabling this bit has the same effect as breaking the mirror.  There is no provision for re-enabling the bit once it has be disabled.


Feedback
----------
Any problems or suggestions should be forwarded to:
RKBUG
or
eugeneb@microsoft.com
