Re: Informix 7 slow over WAN yet fast over LAN

WalidFahmy wrote:
All,
My Informix 7 Server peformance on the Local Area Network is very acceptable,
when connecting a new site using 2 Mbps, client experience was lousy, it took
minutes to open simple forms, which took 1 or 2 seconds on the LAN. We
thought that bandwidth is not enough, so we monitored the WAN port and
utilization did not exceed 30%.
When Monitoring the traffic we found too many PSH,ACK and ACKs going between
Server and Client.
Did anybody see this before ? Can anybody help ?

Two possible causes not mentioned:

1- You note an excess of ACKs, etc. This could be a symptom of the second problem, but another may be the amount of data that's really needed versus the comm buffer size. The buffers default to 4K (max 32K). You can increase the buffer size with the environment variable FETBUFSIZE, set it to 2^15-1 (32767) in the client's environment to get a max sized buffer session setup between the client and the server. This will decrease the number of round trips by a factor of 8 which will help even if 2 is the larger problem.

2- You application is poorly designed so that it is retrieving far more data than it needs and filtering it in software. This will cause the application to run inordinately slower across narrower/slower pipes like your WAN than it does across a fast LAN. Examine the SQL and code to determine if the filtering and the joins are optimal.

Art S. Kagel
.

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