The ATA PASS THRU request is unsuccessful on a Windows XP-based computer or a Windows Server 2003-based computer

On a Microsoft Windows XP-based computer or a Microsoft Windows Server 2003-based computer, a hard disk supports the ATA 48-bit Logical Block Addressing (LBA) feature. However, if the hard disk is smaller than 137 gigabytes (GB), Windows does not handle the ATA PASS THRU request that sets the ATA_FLAGS_48BIT_COMMAND flag. Therefore, the ATA PASS THRU request is unsuccessful.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

No prerequisites are required.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows XP

Windows Server 2003 with SP1, 32-bit versions

Windows Server 2003 with SP2, 32-bit versions

Windows Server 2003 with SP1, 64-bit versions

Windows Server 2003 with SP2, 64-bit versions

Windows Server 2003 with SP1, Itanium-based versions

Windows Server 2003 with SP2, Itanium-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

The ATA 48-bit Logical Block Addressing (LBA) feature is required to support a disk size that is larger than 137 GB. However, there is no requirement in ATA that specifies that the vendor has to implement the 48-bit LBA feature if the disk size is smaller than 137 GB.

On a Windows platform, there is an API named ATA PASS THRU. The ATA PASS THRU API can be used to pass the ATA command from a user-mode Win32 application directly to an ATA controller. In order to use the ATA registers for the 48-bit LBA mode in this API, the application has to set an ATA_FLAGS_48BIT_COMMAND flag. This procedure works well if the hard disk size is larger than 137 GB. However, if the disk is smaller than 137 GB, the Atapi.sys file incorrectly concludes that the following conditions are true:

• The hard disk does not implement the ATA 48-bit LBA feature.
• The ATA_FLAGS_48BIT_COMMAND flag is not suitable for small size hard disks.

The hotfix that is described in this Microsoft Knowledge Base article relaxes restrictions in the Atapi.sys file. This hotfix also enables the backup application to access ATA registers for the 48-bit LBA mode only if the hard disk supports the ATA 48-bit LBA feature. For more information, click the following article number to view the article in the Microsoft Knowledge Base: