Strategies for Boosting File Transfer Throughput Rates (99156)

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Raw I/O

You can increase file transfer throughput with the shipping RAS by putting your workstation in raw I/O mode. Not counting protocol overhead, raw I/O makes possible 95 percent efficiency. It is not enabled by default so as to conserve resources at the server.

To turn raw I/O on you have to go to the wrkheurestics section in the LANMAN.INI file and change bit 14 from 1 to 0. However, if the baud rate is 2400 or less, you should also increase the "netsesstimeout" parameter in LANMAN.INI (to avoid session timeouts on 64K raw I/O blocks). Changing netsesstimeout is not documented anywhere.

Modem Compression

Another way to improve throughput is to turn on compression in modems. Some modems cannot successfully negotiate the correct protocol, and you end up with a lower baud rate phone link than might otherwise be possible, but if all your modems are compatible, it is easy to turn compression on by following the instructions in their documentation. Windows is constrained because it uses the redirector for transparent LAN access, which enables file transfer as well as support for other services such as NetBIOS or named pipes. Because Windows supports all these APIs, it must allow for multiple simultaneous applications to be active and alive, which prevents using strategies such as Laplink uses.

LAN Manager 2.1 PTK Headers

A final method for improving throughput is to use the LAN Manager 2.1 PTK headers with the IBM C/2 compiler, and make the compiler perform all flat-to-selector translations. Put the code below in your file before including the LAN Manager files:

  #undef FAR
   #undef far

   #define FAR     _far16
   #define far     _far16
   #define     syscall     pascal _far16

   {LAN #defines}
   #include <lan.h>

   #undef _syscall