[rrd-users] Using Maximum values to avoid spikes?

[Robert C. Seiwert]

Of course looking at the docs I could be wrong
"Internally, derive works exactly like COUNTER but without overflow checks. So if your counter does not reset at 32 or 64 bit you might want to use DERIVE and combine it with a MIN value of 0."
"NOTE on COUNTER vs DERIVE

by Don Baarda <don.baarda at baesystems.com>

If you cannot tolerate ever mistaking the occasional counter reset for a legitimate counter wrap, and would prefer "Unknowns" for all legitimate counter wraps and resets, always use DERIVE with min=0. Otherwise, using COUNTER with a suitable max will return correct values for all legitimate counter wraps, mark some counter resets as "Unknown", but can mistake some counter resets for a legitimate counter wrap.

For a 5 minute step and 32-bit counter, the probability of mistaking a counter reset for a legitimate wrap is arguably about 0.8% per 1Mbps of maximum bandwidth. Note that this equates to 80% for 100Mbps interfaces, so for high bandwidth interfaces and a 32bit counter, DERIVE with min=0 is probably preferable. If you are using a 64bit counter, just about any max setting will eliminate the possibility of mistaking a reset for a counter wrap."


-----Original Message-----
From: rrd-users [mailto:rrd-users-bounces+rob=vcaglobal.com at lists.oetiker.ch] On Behalf Of Robert C. Seiwert
Sent: Thursday, August 20, 2015 2:35 PM
To: 'Florio, Christopher N' <florio at email.unc.edu>; rrd-users at lists.oetiker.ch
Subject: [GRAYMAIL] Re: [rrd-users] Using Maximum values to avoid spikes?

The problem I think is that COUNTER only detects a reset at the 32bit or 64bit border.

I think that DERIVE would give you a negative spike. You might try DCOUNTER. This is floating point which I know is not ideal for the application. The only substantial difference to COUNTER is that DCOUNTER can either be upward counting or downward counting, but not both at the same time. The current direction is detected automatically on the second non-undefined counter update and any further change in the direction is considered a reset. The new direction is determined and locked in by the second update after reset and its difference to the value at reset.

BTW,  Nice garden!

-----Original Message-----
From: rrd-users [mailto:rrd-users-bounces+rob=vcaglobal.com at lists.oetiker.ch] On Behalf Of Florio, Christopher N
Sent: Thursday, August 20, 2015 2:20 PM
To: rrd-users at lists.oetiker.ch
Subject: [GRAYMAIL] [rrd-users] Using Maximum values to avoid spikes?

Hey all,

I've got a home brew rrd file that I've made to keep track of ISC bind statistics.

I've set the max to 4,000,000,000 .... I acrtually see one of my hosts do 1.5G every night for a couple hours.

/usr/bin/rrdtool create \
/usr/share/cacti/rra/crush_net_unc_edu_query_116761.rrd \ --step 300  \
DS:query:COUNTER:600:0:4000000000 \
DS:notify:COUNTER:600:0:4000000000 \
RRA:AVERAGE:0.5:1:500 \
RRA:AVERAGE:0.5:1:600 \
RRA:AVERAGE:0.5:6:700 \
RRA:AVERAGE:0.5:24:775 \
RRA:AVERAGE:0.5:288:797 \
RRA:MAX:0.5:1:500 \
RRA:MAX:0.5:1:600 \
RRA:MAX:0.5:6:700 \
RRA:MAX:0.5:24:775 \
RRA:MAX:0.5:288:797 \

So, what happens is, if the bind process gets restarted, the data goes back to zero and I get a 4G spike on my graph.

Any ideas on fixing that?  Should I use derive instead of counter to fix it up?

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