Recognizing  LARGE Hard Drives

How to Enable 48-bit Logical Block Addressing Support for ATAPI Disk Drives in Windows XP

SUMMARY

This article describes the Windows XP Service Pack 1 (SP1) 48-bit Logical Block Addressing (LBA) support for ATA Packet Interface (ATAPI) disk drives that can enable the capacity of your hard disk to exceed the current 137 gigabyte (GB) limit.

Note 48-bit LBA support is not enabled and therefore supported without Windows XP SP1. Windows XP Media Center Edition and Windows XP Tablet PC Edition already include SP1.

 

MORE INFORMATION

Windows XP SP1 includes 48-bit LBA support for ATAPI disk drives. With this support, you can use hard disks that are larger than the current 137 GB limit. By default, support is enabled in SP1. To determine if you are running SP1, right-click My Computer and then click Properties. On the General tab, Service Pack 1 will be listed under System.

To determine if you have the latest ATAPI driver, verify that the version of Atapi.sys in your %systemroot%\system32\drivers folder is version 5.1.2600.1135 (or version 5.1.2600.1152 for Windows XP 64-Bit Edition) or later. To do this, follow these steps:

Click Start, and then click Search (or point to Search and then click For Files and Folders).

Type Atapi.sys, and then click Search.

If the Atapi.sys file in your %systemroot%\system32\drivers folder is not found, change your preferences for the Search Companion to search system and hidden folders and then repeat step 2. For additional information about how to search for hidden and system folders, click the following article number to view the article in the Microsoft Knowledge Base: 302347

In your %systemroot%\System32\Drivers folder, Right-click Atapi.sys, and then click Properties.

On the Version tab, note the file version.

If Atapi.sys is not version 5.1.2600.1135 (or version 5.1.2600.1152 for Windows XP 64-Bit Edition), obtain and install the hotfix described in Microsoft Knowledge Base article 331958. For additional information about this hotfix, the following article number to view the article in the Microsoft Knowledge Base: 331958 Hard Disk May Become Corrupted When Entering Standby or Hibernation or When Writing a Memory Dump

By default, the original release of Windows XP Home Edition and Windows XP Professional do not have 48-bit LBA support enabled.

You must meet the following requirements to use 48-bit LBA ATAPI support:

·        You must have a 48-bit LBA compatible BIOS.

·        You must have a hard disk that has a capacity that is greater than 137 GB.

·        You must have Windows XP SP1 installed.

For the original release of Windows XP Home Edition or Windows XP Professional, 48-bit LBA could be enabled for testing purposes by setting a registry value, named EnableBigLba, to 1 in the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Atapi\Parameters\

Warning Data corruption can occur you use this registry value to enable 48-bit LBA support in the original release of Windows XP Home Edition or Windows XP Professional, or if previous versions of Windows that do not support 48-bit LBA out of the box (for example, Windows 2000 or earlier) are installed on a disk partition that was previously created by a 48-bit aware operating system such as Windows XP SP1 that is larger or spans the current addressable limit of 137 GB.

Note: The preceding registry setting is ignored in Windows XP SP1 and later. If you attempt to enable the 48-bit LBA ATAPI support in the original release of Windows XP Home Edition or Windows XP Professional by editing the preceding registry setting and you did not meet the minimum requirements, you may observe the following behavior:

·        The registry value EnableBigLba is disabled. If you have a 48-bit compatible BIOS that can support a hard disk that has a capacity that is greater than 137 GB, only the first 137 GB of the hard disk are addressable. The rest of the hard disk is not used.

·        The registry value EnableBigLba is enabled, but you do not have a 48-bit LBA compatible BIOS and the capacity of the hard disk does not exceed 137 GB:

If you enable the 48-bit LBA ATAPI support by editing the registry setting, but you lack both a 48-bit LBA compatible BIOS and a hard disk that has a capacity that is greater than 137 GB, you have not changed the system. The hard disk continues to function as a standard hard disk.

·        The registry value EnableBigLba is enabled without a 48-bit LBA compatible BIOS, but you have a hard disk with a capacity that is larger than 137 GB.

If you enable 48-bit ATAPI support in the registry and you have a hard disk that has a capacity that is greater than 137 GB, but you do not have a 48-bit LBA compatible BIOS, only the first 137 GB of the hard disk are addressable. The remainder of the hard disk is not used.

To enable 48-bit LBA support by means of an unattended installation with the Microsoft System Preparation (Sysprep) tool:

Copy the following text into Microsoft Windows Notepad and save the text as the 48bitLba.inf file:

[version]

signature="$CHICAGO$"

SetupClass=BASE

 

 

[DefaultInstall]

AddReg=48bitlba.Add.Reg

 

[48bitlba.Add.Reg]

HKLM,"System\CurrentControlSet\Services\Atapi\Parameters","EnableBigLba",0x10001,1

Create a file named Cmdlines.txt, which includes the following lines:

[Commands]
"rundll32 setupapi,InstallHinfSection DefaultInstall 128 .\48BITLBA.INF"

Locate the Sysprep\I386 folder in the Sysprep image, and then create a $OEM$ subfolder in this folder.

Copy the 48bitlba.inf and Cmdlines.txt files into the Sysprep\I386\$OEM$ folder.

In your Sysprep.inf file, add a key named InstallFilesPath to the [Unattended] section. This key must have the following value: InstallFilesPath = "C:\sysprep\i386"

To add the preceding settings to the Images folder, which had been created with the Riprep.exe program:

On the remote installation server that contains the Riprep image, create a Sysprep\I386\$OEM$ folder in the following folder:

RemoteInstall\Setup\Language\Images\Riprep_dir_name\I386\Mirror1\UserData

Note The word "Language" in the preceding path reads "English" for the English language, and "Riprep_dir_name" is the unique name that you selected for the Riprep image.

Copy the 48bitlba.inf and Cmdlines.txt files into the $OEM$ folder.

Modify the Riprep.sif file in the RemoteInstall\Setup\Language\Images\Riprep_dir_name\I386\Templates\Riprep.sif folder (and any other template files for this Riprep image that you may have created), and then add the OemPreinstall and InstallFilesPath values so that they are set up as:

[Unattended]
OemPreinstall = "Yes"
InstallFilesPath = "C:\sysprep\i386"

Close, and then save the file.

OEMs have the ability to turn this support on by means of the Microsoft Windows OEM Preinstallation Kit.

For more information, refer to the OEM Preinstallation Kit

The information in this article applies to:

·        Microsoft Windows XP Tablet PC Edition

·        Microsoft Windows XP Media Center Edition

·        Microsoft Windows XP Home Edition SP1

·        Microsoft Windows XP Professional SP1

·        Microsoft Windows XP 64-Bit Edition Version 2002 SP1