Some programs do not work as expected when large files are opened

Certain programs such as Microsoft Excel and Microsoft Word do not work as expected when you open medium to large files. A network trace shows that the redirector issues sequential reads that are 4 kilobytes (KB) to 8 KB large. The trace shows a high number of small reads posted by program when the large files are read.

This problem occurs because the redirector does not use the ReadAhead feature.

Windows Server 2003

To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base: Note If the application reads large files sequentially, you must manually enter 8 as the value for the registry entry. For more information, see the "MORE INFORMATION" section.

Windows XP

Service pack information

To resolve this problem, obtain the latest service pack for Windows XP. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

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.

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 tool in Control Panel.

Windows 2000

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.

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 tool in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Microsoft Windows XP Service Pack 2.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

The redirector has been enhanced to enable the ReadAhead feature on sequential reads. Therefore, when a program reads 4-KB or 8-KB segments in a sequential manner, the redirector engages the cache manager and prefetches the data to cache by reading a larger set of data.

Also, the following registry entry has been introduced to control the ReadAhead size:The ReadAhead feature is disabled if hotfix 894463 is installed. Therefore, you must manually enter the ReadAheadGranularity registry entry. To do this, following these steps:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then right-click the following registry subkey:
   
   
   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanWorkStation\Parameters
3. On the Edit menu, point to New, and then click DWORD Value.
4. Type ReadAheadGranularity, and then press ENTER.
5. On the Edit menu, click Modify.
6. Click Decimal, type 8 in the Value data box, and then click OK.

Note There are few scenarios where you may have to modify the registry entry . For example, you may have to change this setting on a lossy WAN link or a heavily loaded Terminal server to a setting of 4 ( this setting equals a 16-KB read size). Typically, when Windows reads large files sequentially, the program performs better if the program posts larger read sizes. For more information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base: