[K12OSN] More feedback on Fedora 10 + LTSP

Les Mikesell lesmikesell at gmail.com
Mon Apr 27 17:35:35 UTC 2009

David Hopkins wrote:
> ethtool reports that the link is up and 1000Mb, full duplex. (mii-tool
> says it is 100Mbit but that tool is quite old). dmesg also shows the
> link up at 1000Mb as well.

Is the switch managed so you can check there as well?  You should see no 
errors in the server 'ifconfig' output or the switch interface 
statistics (or at most a couple if you have replugged the connections). 
If the switch isn't managed, it might have a link light indicator that 
shows full/half duplex.

> Now, I tested the throughput between the server and the file server
> using netio.  This reports that I have a sustained throughput of
> 114MB/sec (or about appr 900Mbit/sec) between my servers on the
> network.  Since I am using the same NIC and switches for the thin
> client side, I would expect about the same performance.

Are you testing this with an equal number of concurrent connections as 
where you see tuxtype/math performance fall - and across the same switch 
connections?  Often a duplex mismatch or similar error degrades badly 
with concurrent operations but might not show up with a single 
connection test.

> I then reverted back to the original server, and noticed the same
> performance issue. I swapped out cables but that didn't change
> anything either.
> The load average on the LTSP server was around 1 with 6 clients
> running tuxmath.  Memory was about 1Gb. So, my best guess is a network
> bandwidth issue. Tonight I'll connect my newest server to that switch
> and see if it performs better. Maybe it is just old hardware.

"Old" Gb switch uplinks should work as well as new ones if the cabling 
and configuration is OK.

   Les Mikesell
    lesmikesell at gmail.com

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