RRD

Round Robin Databases by Toby Oetker [1]

In the example below:

start

First date in the database in epoch (seconds since January 1, 1970). date +%s gives current epoch.

step

Expected rate data comes in in seconds

DS:name:type:heartbeat:min:max

Datasource, the raw data to store

type; Most used are GAUGE (set of data) or COUNTER (always increasing data like from a smartmeter)

heartbeat; Maximum time between two enty's. After this time a record with *UNKNOWN* values will be put in.

min, max; Values outside this range will be recorded as *UNKNOWN*

RRA:consolidatefunction:missing:steps:rows

Round Robin Archive, how the raw data will be consolidated

consolidatefunction; [AVERAGE,MIN,MAX,LAST] what to take from the raw data to store

missing; The amount of allowed *UNKNOWN* records that still give a valid result (0,5 means half the data may be missing)

steps; The number of raw data rows to consolidate

rows; The amount of records to keep in the RRA

What timespan is saved depends on the stepsize, the number of steps and the number of rows.

Example:

rrdtool create database.rrd \
        --start 1 \
        --step 10 \
	DS:count1:COUNTER:60:0:999999999 \
	DS:count2:COUNTER:60:0:999999999 \
        DS:gauge1:GAUGE:60:0:1 \
        DS:gauge2:GAUGE:60:0:99999 \
	DS:count3:COUNTER:60:0:99999999 \
	RRA:AVERAGE:0.5:1:60480 \        # One week of 10 seconds data
	RRA:AVERAGE:0.5:6:44640 \        # 31 days of 1 minute data (consolidate 6 10sec records)
        RRA:AVERAGE:0.5:8640:365         # 365 days of 1 day data  (consolidate 8640 10sec records)

RRD's are used to generate graphs.

start

At what time the X-axis starts

DEF:graphname=database.rrd:counter:consolidate

What DS to display

graphname; Name to refer to in other graph commands (like AREA)

database.rrd:counter; DS to display

consolidate; How to handle data if it needs to be consolidated before displaying it.

type:graphname#008000:legend:STACK

How to display the graph

type; Common are LINE, AREA

graphname#000000; Counter and color to display it in

STACK; For subsequent AREA's, stack them instead of displaying over eachother.

Example:

rrdtool graph imagename.png --title "This is a nice graph" \
	--width 800 \
	--vertical-label aLabel \
	--x-grid HOUR:1:HOUR:4:HOUR:1:0:%H \
	--start now-1d \
	--upper-limit 1 -r\
        DEF:graphname1=database.rrd:counter1:AVERAGE \
        DEF:graphname2=database.rrd:counter2:AVERAGE \
        AREA:graphname1#FF0000:legend1 \
        AREA:graphname2#008000:legend2:STACK