transfer times 10x difference

From: Dan Kirkpatrick <dkirk_at_suhep.phy.syr.edu>
Date: Thu, 22 Apr 1999 11:45:33 -0400

Ok... we have a bunch of servers... 3 of which are 100mbps and 6 are 10mbps.
Here's the times of nfs copy/ftp of a ~3.5mb file

10mbps machine --> 10mbps machine 4.3 sec
10mbps machine --> 100mbps machine 7.6 sec
100mbps machine --> 10mbps machine 5.6 sec
100mbps machine --> 100mbps machine 142.5 sec ----WHY?!

I think i've ruled out nfs problems since all machines are using automount
and all are mounted using 2mb read/write cache (I've tried disabling cache
too).
They are all on the same subnet and same Cisco 2916 10/100 switch, and
settings on the switch are pretty much default set when it comes out of the box
the 100mbps machines are set at eprom to do 100mbps, and the switch
autoconfigures as 100mbps, half duplex

I don't think the gateway is the problem since they are all on the same
subnet but how does a machine determine which of 2 gateways to use? All
machines are running /usr/sbin/gated and most or all don't have a
/etc/gated.conf or /etc/gateways file

one 100mbps machine's ifconfig tu0:
tu0: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 128.230.57.16 netmask ffffff00 broadcast 128.230.57.255 ipmtu 1500

one 10mbps machine's ifconfig ln0:
ln0: flags=c63<UP,BROADCAST,NOTRAILERS,RUNNING,MULTICAST,SIMPLEX>
     inet 128.230.57.3 netmask ffffff00 broadcast 128.230.57.255 ipmtu 1500

Any other ideas of why the 10x difference or something I may be missing?


--------------------------------------------------------------------------
Dan Kirkpatrick dkirk_at_phy.syr.edu
Computer Systems Manager
Department of Physics
Syracuse University, Syracuse, NY
http://www.phy.syr.edu/~dkirk Fax: (315) 443-9103
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Received on Thu Apr 22 1999 - 15:48:52 NZST

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