[rrd-users] Flowscan efficiency - Request for input

Rick Blundell rickb at servercove.com
Tue Jun 8 12:33:51 MEST 2004


Hello All.

I am running a Dual Xeon 2.4 HT with 1GB ram.  I am using flow-capture
to store the raw netflow data, and then flowscan to parse the data and
update the rrd files.  I updating 3000 rrds because we have 3000 IPs on
our network, and right now the network is averaging 200mbits daily; if I
were only running one instance of flow-capture/flowscan, it would take
considerably longer than 300 seconds to update the rrds.

What I did was have the cisco export the netflow data stream to two IPs
(which are on the same server), and then run two copies of flow-capture
and flowscan.  This helps a lot, each takes about 150 secs to analyze
its half of the IPs.  My question is what happens as the network gets so
large that the processors cannot keep up?  

Am I pushing the limits of flow-cap/scan too far? Is there some way to
increase effeciency?  Has anyone generated an rrd file for this many IPs
on so much traffic? I really don't want to tell my boss we need a Quad
Xeon system to generate bandwidth graphs.

Here are the commands I am using:

/usr/local/netflow/bin/flow-capture -z0 -w /var/netflow/ft1
IP1/ROUTER/2000 -S5 -V5 -E1G -n 287 -N

/usr/local/netflow/bin/flow-capture -z0 -w /var/netflow/ft2
IP2/ROUTER2/2000 -S5 -V5 -E1G -n 287 -N 0

flowscan (parsing for the first half of the IPs out of /var/netflow/ft1)
flowscan (parsing for second half of the IPs out of /var/netflow/ft2)


Thank You for any input,
Rick Blundell
http://www.netflowguide.com

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