Write Cache on IDE/ATAPI Disks Is Not Flushed on Shut Down

• Microsoft Windows NT Server versions 3.51 and 4.0
• Microsoft Windows NT Workstation versions 3.51 and 4.0

SYMPTOMS

If your computer supports the shut down and power down feature, you may experience one of the following problems:

• CHKDSK runs as your computer starts and reports a dirty volume.
• A blue screen appears and displays the following message:

        STOP 0x0000007B (parameter, parameter, parameter, parameter)
        INACCESSIBLE_BOOT_DEVICE
  

CAUSE

Recent versions of IDE/ATAPI hard disk drives include a write cache. This cache is normally flushed automatically depending on an algorithm by the hard disk manufacturer. On computers that support the shut down and power down feature, the power may turn off before the write cache is flushed.

RESOLUTION

Windows NT 4.0

To resolve this, apply the fix mentioned below or wait for the next service pack.

This hotfix has been posted to the following Internet location:

   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/
   hotfixes-postSP3/ide-fix

Windows NT 3.51

To resolve this, apply the fix mentioned below or wait for the next service pack.

This hotfix has been posted to the following Internet location:

   ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT351/
   hotfixes-postSP5/ide-fix

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 4.0. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

Microsoft has confirmed this to be a problem in Windows NT version 3.51. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

MORE INFORMATION

The IDE/ATAPI specification does not define a command to determine if a write cache is present or to explicitly flush the cache. The Windows NT file system drivers modify the boot sector on startup to indicate a dirty volume. On shut down, the last operation is to modify the boot sector again to mark the volume clean. This last write is cached in the cache of the disk. If the power is removed too early, this sector is not written at all and the volume is still marked dirty. If the power disappears during the physical write to the disk, the boot sector is corrupt and the blue screen occurs.

The fix to this problem is to send an IDLE command to the drive as the last command at shut down. This synchronous command ensures that the write cache is flushed.