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KB#00838-Recommendations for improving performance when remotely connecting

Title:

Recommendations for improving performance when remotely connecting to a Windows NT 4.0 Server

Description:

Recommending a T1 line is the best answer, but obviously not a realistic answer since most users will RAS in via a modem. The following information better helps to understand how to optimize the remote access connection with Visual PRO/5 and PRO/5 Data Server. 

The overall performance really depends on: 
        1) How much data will be sent over the pipe? 
        2) What are the end users' expectations regarding the performance? 

The first step is to quantify how much data (including loading of programs, reading/writing of data files, etc.) they will be dealing with. Note that the actual amount of data transferred will be larger due to protocol handshaking and the like. 

The second step involves user expectations and what bandwidth will meet those expectations. In order to do this, take the amount of data transferred and the user expectations and determine the desired bandwidth required to cover both. 

*********** 

As a rudimentary example, let's say Visual PRO/5 is run local to avoid transferring the executable (which is in excess of 1MB) over the line. Once running, the application is LOADed which is 50Kb. It calls several other programs totalling 100kb. The application starts and requests data required in a report or record update and reads/writes 350Kb. These 4 steps - from startup of VP5 to completing a simple task at least 500Kb of data has been transferred (although we should probably add more due to overhead). They want this process to take place relatively quickly. 
Over a 28.8kbs modem, this would take: 

        28.8 kbits/s divide by 8bits/byte = 3.6kb/s 
        3.6kb/s * Xsec = 500kb 
        time = 2.3 minutes 

Add in some overhead and you're talking a few minutes - is this too long? If so, decrease the amount of data or increase the bandwidth. 

You can decrease the amount of data transferred by: 

1) Load VP5 locally. Otherwise, you'd have to transfer the executable which would take several minutes over a modem 
2) ADDR your programs. This way they are cached in memory and don't have to be LOADed again over the line. 
3) Also, use MODE=PERSIST to keep a connection to the PRO/5 Data Server open. 

Depending on how the application is structured, it might be possible to get some performance improvement by opening a file or directory using the persist mode. To do this, add a line to the beginning of the application's main program that looks like: 

        OPEN(391,mode="PERSIST")"/<servername>." 

This prevents the Visual PRO/5 client from closing the data server connection every time there aren't any files open via the PRO/5 Data Server; this includes maintaining a connection if any of the application programs have BEGINs in them. 

4) Finally, locally license the Visual PRO/5 on the remote PC. The bottom line is the more you can do locally the better the overall performance of the entire network and certainly a remote connection. 



Last Modified: 03/29/2000 Product: Visual PRO/5 Operating System: Windows NT Windows NT

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