Microsoft KB Archive/241672

= File Transfers Between Computers Are Slower Than Expected =

Article ID: 241672

Article Last Modified on 11/1/2006

-

APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition

-



This article was previously published under Q241672



SYMPTOMS
File transfers between Windows NT 4.0-based computers with similar names are slower than expected. A network trace shows that the data transfer size is 512-byte increments, rather than the 4,096-byte or larger default size used by Windows NT.



CAUSE
A problem in the redirector (Rdr.sys) causes the workstation to incorrectly mark a connection to a remote server as "loopback." This occurs when the remote server has a NetBIOS name that is a subset of the local NetBIOS computer name. For example, a connection to a server named Test is incorrectly considered a loopback connection from workstations named Testx, Test1, Testabc, and so on.

The redirector treats loopback connections differently than it does remote connections. On connections to remote servers, the redirector makes an initial read or write request of 512 bytes and then increases the request size if both computers are capable of handling larger requests. On loopback connections, the entire transfer is in 512-byte increments. Making these small read and write requests generates network overhead, and the request takes longer to finish.



RESOLUTION
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English-language version of this fix should have the following file attributes or later:   Date      Time    Size     File name  Platform --  09/14/99  01:08p  265,008  Rdr.sys    Intel 09/14/99 01:07p  512,144  Rdr.sys    Alpha



STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0.

Additional query words: slow performance core mode raw

Keywords: kbhotfixserver kbqfe kbbug kbfix KB241672

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.