When a Windows Vista-based computer is used as a file server, users access files by using long-term Server Message Block (SMB) requests. By default, only 10 SMB requests can be sent to the server at the same time. All other SMB requests are not answered. Therefore, the user of a client computer may receive an error message when the user tries to access files by using long-term SMB requests.
Note Unlike typical SMB requests, a long-term SMB request remains open until it is answered by the server. A typical long-term SMB request is the NotifyChange SMB request (NT_TRANSACT_NOTIFY_CHANGE).
Most SMB requests are processed immediately. However, long-term SMB requests may cause a problem.
Service pack informationTo resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
Hotfix informationTo resolve this problem, apply the following hotfix. This hotfix lets you use the MaxMpxCt registry entry to configure the maximum number of concurrent SMB requests. You can set the value of MaxMpxCt to a maximum of 255.
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.
PrerequisitesNo prerequisites are required.
Restart requirementYou must restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any other hotfixes.
Registry informationWarning 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.
To enable this hotfix, follow these steps:
- Click Start, type regedit in the Start Search box, and then press ENTER.
- Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Lanmanserver\Parameters
- On the Edit menu, point to New, and then click DWORD Value.
- Type MaxMpxCt, and then press ENTER.
- Right-click MaxMpxCt, and then click Modify.
- In the Value data box, type a value, and then click OK.
Note You can set the maximum number of concurrent SMB requests to a value from 10 through 255. The default value is 10.
- Exit Registry Editor.
File informationThe 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 Vista, 32-bit versions
|File name||File version||File size||Date||Time||Platform|
|Update.mum||Not applicable||2,449||23-May-2007||14:21||Not applicable|
|X86_0eff413cdf04672e2f44fa972dad413c_31bf3856ad364e35_6.0.6000.20603_none_647dc4ac50e1f375.manifest||Not applicable||697||23-May-2007||14:21||Not applicable|
|X86_eeac48e6eab426417e839bddcc03b81b_31bf3856ad364e35_6.0.6000.20603_none_2b2632e4f8a9474c.manifest||Not applicable||700||23-May-2007||14:21||Not applicable|
|X86_microsoft-windows-smbserver-v1_31bf3856ad364e35_6.0.6000.20603_none_d89dc6781267f58c.manifest||Not applicable||4,929||23-May-2007||14:23||Not applicable|
|X86_microsoft-windows-smbserver_31bf3856ad364e35_6.0.6000.20603_none_f79b461606cfdb48.manifest||Not applicable||57,535||23-May-2007||14:23||Not applicable|
|Smbserver-ppdlic.xrm-ms||Not applicable||3,131||22-May-2007||16:06||Not applicable|
Windows Vista, 64-bit versions
|File name||File version||File size||Date||Time||Platform|
|Amd64_3e38cd74a229847467a7cc88a7029aae_31bf3856ad364e35_6.0.6000.20603_none_66a60fa701a070b5.manifest||Not applicable||701||23-May-2007||14:21||Not applicable|
|Amd64_bc1e6a8a7abdd81dd99d59d04e8e2895_31bf3856ad364e35_6.0.6000.20603_none_86910b32ad4dca86.manifest||Not applicable||704||23-May-2007||14:21||Not applicable|
|Amd64_microsoft-windows-smbserver-v1_31bf3856ad364e35_6.0.6000.20603_none_34bc61fbcac566c2.manifest||Not applicable||5,196||23-May-2007||14:28||Not applicable|
|Amd64_microsoft-windows-smbserver_31bf3856ad364e35_6.0.6000.20603_none_53b9e199bf2d4c7e.manifest||Not applicable||57,571||23-May-2007||14:28||Not applicable|
|Update.mum||Not applicable||2,463||23-May-2007||14:21||Not applicable|
|Smbserver-ppdlic.xrm-ms||Not applicable||3,131||22-May-2007||11:48||Not applicable|
- The value of the MaxMpxCt entry on the server
- The value of the MaxCmds entry on the client computer
On a Windows Vista-based server, the MaxMpxCt entry, the MaxWorkItems entry, and the Size entry are located in the following registry subkey:
- Set the value of MaxWorkItems to at least four times the value of MaxMpxCt. By default, MaxWorkItems is set to 64 in Windows Vista. You can set this entry to a maximum of 1,024. We recommend that you use this setting only on a computer that has sufficient memory. If you use the maximum setting, we recommend that you use at least 1 gigabyte (GB) of memory.
- By default, the value of the Size entry is 1 in Windows Vista. Set the Size entry to at least 2. If you experience problems, set the Size entry to 3.
- A value of 1 optimizes Windows Vista for local applications.
- A value of 2 balances resource usage between local application and remote applications.
- A value of 3 optimizes Windows Vista for network activity.
For more information about this problem in Microsoft Windows XP, click the following article number to view the article in the Microsoft Knowledge Base:
Article ID: 937082 - Last Review: Oct 8, 2011 - Revision: 1