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Q192496: Slow Write Performance Using IBM DOS Lan Requester

Article: Q192496
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): 
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation version 4.0 
- Microsoft Windows NT Server version 4.0 
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SYMPTOMS
========

Write operations are a magnitude slower that read operations against a server
running Windows NT when using IBM DOS LAN Requester.

MORE INFORMATION
================


In the Network Monitor trace below, the client uses a send window of 1. With this
send window, the client does not send any more frames before the last frame has
been acknowledged. When Windows NT receives this frame, it does not immediately
acknowledge it to optimize the number of frames sent in return. If several
frames arrive in a short period of time, they can be acknowledged in one reply.
When the server has any data to send back to the client, the acknowledgement can
be sent together (piggybacked) with the response.

To use these optimizations (also known as delayed acknowledgement), Windows NT
NetBEUI waits for a maximum of 150 ms (T2), and then sends an acknowledgement.

This causes a round-trip delay of about 200 ms for each frame, seriously
degrading throughput.

303 17.903 SMB C write block raw, FID = 0x802, Write 0xfd8 of 0xabec at
0xabec
304 18.086 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x5E
305 18.089 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
306 18.286 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x5F
307 18.289 NETBIOS Data Only Last (0x16): LSN = 0x04, RSN = 0x3D, Length =
2028
308 18.292 NETBIOS Data Ack (0x14): LSN = 0x3D, RSN = 0x04
309 18.292 SMB     R write block raw
310 18.292 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x26
311 18.293 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x27
312 18.293 NETBIOS Data Ack (0x14): LSN = 0x04, RSN = 0x3D
313 18.486 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x61
314 18.490 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
315 18.687 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x62
316 18.691 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
317 18.887 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x63
318 18.890 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
319 19.087 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x64
320 19.090 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
321 19.287 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x65
322 19.291 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
323 19.489 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x66
324 19.492 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
325 19.688 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x67
326 19.691 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
327 19.888 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x68
328 19.891 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028
329 20.089 LLC     RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x69
330 20.092 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D,
Length = 2028

RESOLUTION
==========

Use an updated client that uses a send window or sets the POLL bit in the LLC
header for immediate acknowledgements or Change MaximumIncomingFrames in the
registry to 1. However, this setting will degrade performance for all clients.

For additional information, please see the following article in the Microsoft
Knowledge Base:

  Q102998 REG: Network Services Entries, Part 4


For information regarding this product, please connect to IBM's main Web page:

  http://www.software.ibm.com

The third party products discussed here are manufactured by a vendor independent
of Microsoft; we make no warranty, implied or otherwise, regarding these
products' performance or reliability.

Additional query words: slow performance delayed nbf
======================================================================
Keywords          :  
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400
Version           : WinNT:4.0
Issue type        : kbprb

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