[CentOS] CPU usage over estimated?

Les Mikesell lesmikesell at gmail.com
Fri Jun 5 17:44:44 UTC 2009

nate wrote:
> I wrote a few scripts that get CPU usage and feed it into SNMP for
> retrieval for my cacti systems.
> My company used to rely on the built in linux SNMP stuff for cpu
> usage(before I was hired) and they complained how it always seemed
> to max out at 50%(on a dual cpu system).
> I've been using my own methods of CPU usage extraction using sar
> for about 6 years now and it works great, only downside is sar
> keeps being re-written and with every revision they make it harder
> and harder to parse it(RHEL 3 was the easiest by far).
> Sample graph -
> http://portal.aphroland.org/~aphro/cacti-cpu.png
> That particular cacti server is collecting roughly 20 million data
> points daily(14,500/minute). *Heavily* customized for higher
> scalability.

Have you looked at OpenNMS for this?  It's java with a postgresql 
backend for some data and jrobin (equivalent to rrd) for some.  It needs 
a lot of RAM and has the same i/o bottleneck as anything else updating 
large numbers of rrd files but otherwise is pretty scalable and includes 
a lot more features than cacti.

   Les Mikesell
    lesmikesell at gmail.com

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