[rrd-developers] Re: Min Max / Spikes
rader at teak.wiscnet.net
Sun Feb 6 21:19:08 MET 2000
> I am rather new to RRD and have a question that (probably) has been asked
> before (many times).
> I occasionally get (unexplained) spikes in graphs when polling goes down
> or if a router is rebooted.
> I realize I must set thge min/max values. what are the vales ?
> Is it assuming full duplex ? Is it time dependent ?
> for example.
> interfaces.ifTable.ifEntry.ifDescr.40 = "Serial2/0/0/28:0"
> interfaces.ifTable.ifEntry.ifSpeed.40 = Gauge: 1536000
> should the max for 40 be 1536000 or (1536000 * 300) or (1536000 * 300 * 2)
I'm pretty sure you should use 192000! [Someone please correct
me if I'm wrong...]
Here's why: man "rrdcreate" sez "[f]or a traffic-COUNTER type
DS this would be the max [...] data-rate expected from the
device." The SNMP ifSpeed OID is max data-rate in bits/sec.
Unfortunately, SNMP counters register bytes/sec. So you need
to convert from bits/sec to bytes/sec (1/8 conversion factor)
so you should use 192000 (1536000/8.)
> what about other interface types ?
Interface type doesn't matter: even with half duplex mediums,
the wire may (in theory at least) be 100% utilized going just
one way and thus the max value should be full wire speed.
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