Performance is significantly reduced when you copy or write small files from a computer that is running Windows Vista or Windows Server 2008 into a shared folder that is hosted on a computer that is running Windows Vista or Windows Server 2008

From a computer that is running Windows Vista or Windows Server 2008, you copy or write some small files into a shared folder that is hosted on a computer that is running Windows Vista or Windows Server 2008. In this situation, the writing performance is significantly reduced.

You find that there is a performance reduction when you compare this writing performance to the performance of the following operations:

• Copying or writing files from a computer that is running Windows Server 2003 into a shared folder that is hosted on a computer that is running Windows Server 2003.
• Copying or writing files from a network file system (NFS) client to an NFS server.

Additionally, you may find that the Server Message Block (SMB) 2.0 protocol is being used to copy or write files.

The SMB 2.0 protocol calls a function to set file information before it performs a network write action. In Windows Vista and in Windows Server 2008, this function is called when a specific amount of data must be written. This amount of data is a multiple of the volume cluster size of the shared folder. By default, the volume cluster size of the shared folder is set to 1 byte. This small size causes the function to be called more frequently. Therefore, excessive function calls reduce the writing performance significantly.

Hotfix information

Important Windows Vista and Windows Server 2008 hotfixes are included in the same packages. However, only one of these products may be listed on the �Hotfix Request� page. To request the hotfix package that applies to both Windows Vista and Windows Server 2008, just select the product that is listed on the page.

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 the problem described in this article. 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

To apply this hotfix, your computer must be running Windows Vista Service Pack 1 (SP1) or Windows Vista Service Pack 2 (SP2).

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
No prerequisites are required for computers that are running Windows Server 2008.

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 Global 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 Vista and Windows Server 2008 file information notes

• The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.

  Version	Product	SR_Level	Service branch
  6.0.6000.16xxx	Windows Vista	RTM	GDR
  6.0.6000.20xxx	Windows Vista	RTM	LDR
  6.0.6001.18xxx	Windows Vista and Windows Server 2008	SP1	GDR
  6.0.6001.22xxx	Windows Vista and Windows Server 2008	SP1	LDR
  6.0.6002.18xxx	Windows Vista and Windows Server 2008	SP2	GDR
  6.0.6002.22xxx	Windows Vista and Windows Server 2008	SP2	LDR

• Service Pack 1 is integrated into the original release of Windows Server 2008.

For all supported x86-based versions of Windows Vista SP1 or of Windows Server 2008

For all supported x86-based versions of Windows Vista SP2 or of Windows Server 2008 SP2

For all supported x64-based versions of Windows Vista SP1 or of Windows Server 2008

For all supported x64-based versions of Windows Vista SP2 or of Windows Server 2008 SP2

For all supported Itanium-based versions of Windows Server 2008

For all supported Itanium-based versions of Windows Server 2008 SP2

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

To work around this problem, trigger an information query before you perform any network write actions. To do this, open the shared folder in Windows Explorer or open a command prompt, type the following command, and then press ENTER:Note When you run this command, replace the server placeholder with the name of the server, and replace the share placeholder with the name of the shared folder.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: