RE: TCP/IP Performance

1. Talk to the HA vendor to find out roughly how big a data packet is,
then adjust the MTU of the Ethernet interfaces & the WAN link (routers,
etc.) to accommodate that size.  You could be having problems with
fragmented packets & their overhead.

2. Up the TCP/IP send/receive buffers.  By default there are rather
small.

3. Make sure the lines are running 100MB Full Duplex.  Half Duplex can
cause problems.

4. Is your 400's system bus becoming saturated?  Can the Etherenet
adapters be moved to a less-utilized bus?

5. Try setting the TOS parm of the IP interface to *MINDELAY.

These, of course, would apply to both the source & target systems.
Updating a setting on one box may not help unless the other box is
updated as well.

HTH, John

-----Original Message-----
From: mgarton@xxxxxxxxxxxxxxx [mailto:mgarton@xxxxxxxxxxxxxxx] 
Sent: Wednesday, April 23, 2003 9:08 AM
To: midrange-l@xxxxxxxxxxxx
Subject: TCP/IP Performance


My company is running one of the High Availability products to replicate

(via sockets) our corporate system to our DR system in a data center 400

miles away.  We have a 9 Mbps WAN link that is dedicated to this
process. 
The problem is that we are not able to fully utilize the pipe even
though 
the HA product shows that there are transactions backed up waiting to be

sent.  Currently we are only able to utilize 5 to 6 Mb of the pipe.  We 
have ran performance reports on production system (model 830, V5R2) and 
there are no errors on the line and the IOP is not over utilized.  We
have 
set up a separate memory pool for the HA application.  It doesn't seem
to 
make a difference if the system is busy or not.  I have tried working
with 
the HA product vendor, our network people, and the communications vendor

and nobody has found anything problems.  Does anyone have any other 
suggestions?  I was wondering if there is something that we could tweak
in 
the TCP attributes on the production system to get better throughput. 
Thanks in advance.


Mark Garton
Disaster Recovery Team Leader
O'Reilly Auto Parts

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