Performance Improvement for Redirector/Server Connections Involving Small File Operations

ID: Q236316

The information in this article applies to:

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

SYMPTOMS

Programs that perform numerous small file operations, such as locking and unlocking files or writing small records, may experience slow performance.

CAUSE

This problem occurs because the combination of "Nagling" (a TCP concept described in the Microsoft Knowledge Base and white papers) and TCP delayed acknowledgment can cause unnecessary network delay when numerous small file operations are outstanding between a client and server. More details on Nagling are available at the following Microsoft Web site:

ftp://ftp.microsoft.com/bussys/winnt/winnt-docs/papers/TCPIMP2.EXE

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:

http://www.microsoft.com/windows/servicepacks/

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

For information on obtaining the individual software update, contact Microsoft Product Support Services. 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

NOTE: The optimization that is described in this article may lead to a performance decrease in some scenarios. This has been observed when a computer with the fix installed accesses a server on the network that does not have the fix. When the client performs many file locks and small reads, performance may be slower than between two computers without the fix. In this case, Microsoft recommends deploying SP6a on all the computers. If deploying SP6a is not an option, the following fix is still available that incorporates the change as a post-SP5 hotfix.

The English version of this fix should have the following file attributes or later:


   Date      Time     Size      File name   Platform
   --------------------------------------------------
   06/28/99  01:10p   123,120   Netbt.sys   x86
   06/28/99  01:09p   224,144   Netbt.sys   Alpha

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0. This problem was first corrected in Windows NT 4.0 Service Pack 6.

MORE INFORMATION

The Netbt.sys driver has been modified to disable nagling in the TCP stack for NetBT connections.

Additional query words: nagle tcpip netbt

Keywords : kbbug4.00 kbfix4.00 NT4SP6Fix
Version : winnt:4.0
Platform : winnt
Issue type : kbbug