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Q126432: SNA Server Windows Client Memory Tuning

Article: Q126432
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s): 
Keyword(s): kbnetwork sna4
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0 
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SUMMARY
=======

The following tuning suggestions can reduce conventional memory usage on Windows
3.x and Windows for Workgroups 3.x clients running the SNA Server Windows 3.x
client software. If the machine is running low on available conventional memory
(memory between zero and one megabyte), you may see the following problems, no
matter how much RAM you have installed:

- One of the following error message appears:

  Out of Memory

  SNA Server Error 546: Cannot establish connection with SNA Server

  NAP not started

- The SNA Server Windows client icon (WNAP.EXE) does not maintain its sponsor
  connection

- A 5250 emulator displays the following APPC error:

  

     Primary return code = F011        (AP_UNEXPECTED_DOS_ERROR)
     Secondary return code = 00000008  (out of memory)

- Applications the do not properly handle low memory situations cause general
  protection (GP) faults or stop responding (hang).

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

Windows client memory tuning suggestions:

SNA Server Windows Client Memory Allocation
-------------------------------------------

By default, WNAP reserves enough internal buffers to handle connections through
several servers. If you only connect through one or two SNA Servers, you can add
the following entry to the [wnap] section of WIN.INI:

  "maxpipes=6" (without the quotation marks)

This entry determines the number of communication buffers that the SNA client
software allocates, regardless of the client network interface selected (named
pipes, IPX/SPX, TCP/IP or Banyan IP).


Stop and restart WNAP so this change can take effect.


Disabling Network DDE on Windows for Workgroups Version 3.11 Machines
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A significant amount of conventional memory can be gained by disabling Network
DDE, if it is not being used. To do this, run the Windows for Workgroups 3.11
Control Panel, choose Network, choose Startup, and clear the Network DDE check
box. Quit and restart Windows for Workgroups so this change can take effect.


You can make more conventional memory available by removing any unnecessary
drivers or terminate-and-stay-resident (TSR) programs from the configuration,
and maximizing the use of available upper memory block (UMB) areas if MS-DOS 5.0
or later is being used.

Identify Low Memory Situations
------------------------------

You can use the Heap Walker utility (HEAPWALK.EXE), included with the Windows 3.1
SDK, to help identify low conventional memory situation in Windows:


- Select the Sort/Address option to view memory allocation from low to high
  memory addresses. Conventional memory addresses start with 000xxxxx while
  virtual addresses start with 80xxxxxx.

- All segments which appear as Fixed memory (where the FLG field is set to F)
  cannot be moved or discarded by Windows. Low conventional memory problems
  occur when excessive Fixed memory regions occupy conventional memory space,
  and very few free conventional memory areas are available, even though the
  may be large amounts of virtual memory available.

- You can save Heap Walker information to a file called HWG0x.TXT (where x
  increments from 0 - 9) by choosing Save from the file menu.

If HEAPWALK is not available, you can run MEM /C (before running Windows or
Windows for Workgroups) to determine how much free conventional memory is
available before Windows is loaded. You cannot view Windows memory allocation.


Additional query words: prodsna tcp/ip gpf

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Keywords          : kbnetwork sna4 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version           : WINDOWS:2.0,2.1,2.11,3.0,4.0

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