RRDTool data source type selection

Question

I have a question related to RRDTool DST. I need to create a database in such a way that even the data is the same (for example, I have six entries per hour with the same value). RRDTool must calculate the AVERAGE of this data.

I'm creating database with following command:

rrdtool create test.rrd --step 15 DS:na:GAUGE:15:0:U RRA:AVERAGE:0.99:1:244 RRA:AVERAGE:0.99:24:244 RRA:AVERAGE:0.99:168:244 RRA:AVERAGE:0.99:672:244 RRA:AVERAGE:0.99:5760:374

And I'm updating database with following command:

rrdtool update test.rrd 1296231519:0.6039 

After making 10 entries with the same value (changing timestamp but the same value), I do rrdtool dump test.rrd test.xml, but I don't see any data... It does not contain the 10 entries.

After making 10 entries with a different value (changing timestamp and changing value), I do the dump of database and there are the 10 entries I have done.

What I'm doing wrong? Maybe DST 'GAUGE' is wrong on creation of rrd?

Answer 1

The data source type is fine, but you have set the update interval to 15 seconds and ALSO set the maximum update interval to 15 seconds ... I would suggest raising to maximum to 30 seconds as you might not be able to provide an update exactly every 15 seconds ...

rrdtool create test.rrd --step 15 \
    DS:na:GAUGE:30:0:U \
    RRA:AVERAGE:0.99:1:244 \
    RRA:AVERAGE:0.99:24:244 \
    RRA:AVERAGE:0.99:168:244 \
    RRA:AVERAGE:0.99:672:244 \
    RRA:AVERAGE:0.99:5760:374

Further your first RRA will keep data for 61 minutes in 15 second intervals, the second one for 144 hours in 6 minute intervals. These seem odd numbers to me ... is this intentional? Maybe have a look at the rrdtool tutorials to see how others approach this.