File Transfers Between Computers Are Slower Than Expected

ID: Q241672

The information in this article applies to:

Microsoft Windows NT Server version 4.0
Microsoft Windows NT Workstation version 4.0

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 that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

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     x86
   09/14/99  01:07p               512,144  Rdr.sys     Alpha

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0.

Additional query words: slow performance core mode raw

Keywords : kbbug4.00 kbfix4.00
Version : winnt:4.0
Platform : winnt
Issue type : kbbug