Follow-up note to the commit message. This patch fixes AND enhances the rrds. Although the rrd plugin appeared to give you full control over the creation of rrd's in fact, some things were - behind the scenes - hard coded. This change fixes that.
It also gives you full control over the amount and granularity of the data
recorded in the rrds.
We now ask for FOUR pieces of information, as follows, with the default
values in ()s:
Dump Interval (300) seconds - which specifies how often data is stored.
Dump Hours (72) Specifies how many hours of 'interval' data is stored
permanently.
Dump Days (90) Specifies how many days of hourly data is stored
permanently.
Dump Months (36) Specifies how many months of daily data is stored
permanently.
You can achieve the old-style results with interval 300, hours 100, days 0,
months 0. This will record the same 1200 5m samples as ntop does in
versions through 2.1.90.
The new version creates 5 RRAs (Round Robin Archives) (the interval data,
min, max, hourly and daily) vs. the old version which created only three
(interval, min and max).
WARNING: Changes to these values will ONLY affect NEW rrds. And there is no
conversion I'm aware of - although it ought to be possible, the rrdtool
stuff is so minimally documented... I haven't figured it out.
Note: The rrd graph function does not handle the situation where part of
the data is in one RRA and part in another.
If, for example, you tell ntop to record 2 hours of data at 15s intervals
and then 30 days of hourly data, a 4 hour report will not show the 1st and
2nd hour of details and 3rd and 4th hour at the hourly resolution. It
will - as in the attached .png files - only show the hourly buckets.
If you create a 2 hour chart, you'll then see the details (see the 2nd
attached png).
You need to be aware of this when setting the values. If you want a weekly
detailed report, you need to tell ntop to record 168 hours of interval data.
744 hours for a 31-day month.
If you want to see the contents of the rrd, I use
$ rrdtool dump xxxx.rrd | grep -v NaN | less
-----Burton
<<attachment: rrdPlugin-4hour.png>>
<<attachment: rrdPlugin-2hour.png>>
