[collectd] smnp plugin, 4.10.3 vs 5.0

Mariusz Gronczewski xani666 at gmail.com
Tue Aug 9 15:58:23 CEST 2011

2011/8/9 Sergey <a_s_y at sama.ru>:
> On Tuesday, August 09, 2011, Mariusz Gronczewski wrote:
>> Maybe add network plugin config to send data anywhere, then fire
>> wireshark and see what snmp values collectd get and how it parses it
>> (new versions of wireshark have builtin collectd protocol decoder)?
> I'll attemt it.
>> Kinda looks like it uses 32 bit counters, with COUNTER type its not
>> problem if it doesnt overflow more than once per cycle, but DERIVE
>> type saves NaN when counter have smaller value than last one.
> I've thought about it, but 4.10.3 works with 32 bit counters.
> I'll try to use 64 bit counters, but it is possible bug.
2^32 is ~ 4 295 milions, after that counter overflows
so about 4 GB before counter overflows
default checks are every 10
in 4.x default type for if_octets is COUNTER so if it overflows it
calculates "right" value and inserts that
 which fails if there is more than 1 overflow between checks OR if
counter gets "zeroed" (restart of device, VPN goin down/up),
 which produces spikes on graph
in 5.x default type is DERIVE so when it overflows it inserts NaN into
database = empty line on graph
 the rarer is your probe rate the more visible that is, and ofc
increases with traffic (as shown on graphs)

You could probably fix it by "importing" types.db from 4.x collectd
but using 64 bit snmp counters would be better :)

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