Disk Concepts and Troubleshooting

Disk problems can occur that do not involve the MBR, partition table, extended partition table, or boot sector. Typically, the Windows 2000 disk tools cannot be used to troubleshoot these disk problems.

Stop 0x0000007B — Inaccessible Boot Device

This Stop message, also known as Stop 0x7B, indicates that Windows 2000 lost access to the system partition during the startup process.

This error can be caused by a number of factors, including the failure of the boot device driver to initialize, the installation of an incompatible disk or disk controller, an incompatible device driver, disk cabling problems, disk corruption, viruses, or incompatible logical block addressing (LBA).

The system BIOS allows access to fixed disks that use fewer than 1024 cylinders. Many later disks, however, exceed 1024 cylinders. LBA is used to provide support for these disks. Such support is often built into the system BIOS. However, there are potential problems with LBA, such as:

  • If partitions are created and formatted with LBA disabled, and LBA is subsequently enabled, a STOP 0x7B can result. The partitions must be created and formatted while LBA is enabled.

  • Some LBA schemes are not compatible with Windows 2000. Check with your vendor.



Changing LBA modes from one scheme to another can force you to recreate and reformat the partitions.

For more information about Stop message 0x7B, see Windows 2000 Stop Messages in this book.

Volume Displays as Unknown

If you create and format a volume with NTFS, FAT16, or FAT32, but you cannot access files on it, and Disk Management displays the volume as Unknown, the boot sector for the volume might be corrupted. For NTFS volumes, there are two other possible causes for a volume to display as Unknown:

  • Permissions for the volume have been changed.

  • The master file table (MFT) is corrupted.

The boot sector can be corrupted by viruses. For more information about cleaning an infected computer, see Viruses earlier in this chapter.

Permission problems can occur when you perform the following tasks:

  • Create a second volume.

  • Remove the group Everyone from the access control list (ACL).

  • Grant access to a specific user.

The single user has normal access, but if other users log on, or if Windows 2000 is reinstalled, Disk Management shows the drive as Unknown. To correct this problem, log on as an administrator and take ownership of all folders, or return full control to the group Everyone.

If the MFT file is corrupted, there is no general solution, and you need to contact Microsoft Product Support Services.

CMOS Problems

The CMOS typically stores configuration information about the basic elements of the computer, including RAM, video, and storage devices. If the CMOS is damaged or incapable of retaining its configuration data, the computer might be unable to start.

Each manufacturer and BIOS vendor can decide what a user can configure on the CMOS, and what the standard configuration is. You can access the CMOS by using either a keyboard sequence at startup or a software tool, depending on the manufacturers specifications. It is recommended that you record or print all CMOS information.

The computer uses the CMOS checksum to determine if any CMOS values have been changed other than by using the CMOS Setup program. If the checksum is not correct, the computer cannot start.

After the CMOS is correctly configured, any CMOS problem is usually caused by one of the following problems:

  • A weak battery, which can happen when the computer has been turned off for a long time.

  • A loose or faulty connection between the CMOS and the battery.

  • A damaged CMOS caused by static electric discharge.

Cables and Connectors

Another source of disk problems can be cabling and connectors. Cables can go bad, but if the cable works initially, it is likely to work for a long time. When new disks are added to the computer, check for cabling problems. New problems might stem from a previously unused connector on an existing cable or from a faulty, longer cable used to connect all the disks that might have replaced the working original. Also check the connections to the disk themselves. If the cables are tightly stretched, one or more connectors may work themselves loose over time, resulting in intermittent problems with the disks.

If your system has small computer system interface (SCSI) adapters, contact the manufacturer for updated Windows 2000 drivers. Try disabling sync negotiation in the SCSI BIOS, checking the SCSI identifiers of each device, and confirming proper termination. For enhanced integrated drive electronics (EIDE) devices, define the onboard EIDE port as Primary only . Also, check each EIDE device for the proper master, slave, or stand-alone setting. Try removing all EIDE devices except for hard disks.

To make sure that any new disks and disk controllers are supported, see the Microsoft Windows 2000 Hardware Compatibility List (HCL) link on the Web Resources page at http://windows.microsoft.com/windows2000/reskit/webresources .