[rrd-users] RRDTool Aggregation Inaccuracies.

Tue Jul 7 21:46:11 CEST 2009

Looks like I did a poor job pasting the commands I've been using. Am I wrong
to assume that I can add the max value from each independent RRD? This page
seems to suggest so, but I do not understand why:
http://www.vandenbogaerdt.nl/rrdtool/min-avg-max.php

Straight from the command line:

/usr/bin/rrdtool graph 1-day.png --end now --start e-1d --imgformat PNG \
DEF:service_0=database_0.rrd:audience:MAX
CDEF:users_0=service_0,UN,0,service_0,IF \
DEF:service_1=database_1.rrd:audience:MAX
CDEF:users_1=service_1,UN,0,service_1,IF \
DEF:service_2=database_2.rrd:audience:MAX
CDEF:users_2=service_2,UN,0,service_2,IF \
DEF:service_3=database_3.rrd:audience:MAX
CDEF:users_3=service_3,UN,0,service_3,IF \
DEF:service_4=database_4.rrd:audience:MAX
CDEF:users_4=service_4,UN,0,service_4,IF \
DEF:service_5=database_5.rrd:audience:MAX
CDEF:users_5=service_5,UN,0,service_5,IF \
CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
\
LINE1:aggregate_users#000000 \
VDEF:peak_users=aggregate_users,MAXIMUM \
VRULE:peak_users#0000FF COMMENT:\\n \
GPRINT:peak_users:'Peak of %.0lf users' \
GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'

OUTPUT: http://www.androidmilitia.com/rrdtool/1-day.png

/usr/bin/rrdtool graph 1-week.png --end now --start e-1w --imgformat PNG \
DEF:service_0=database_0.rrd:audience:MAX
CDEF:users_0=service_0,UN,0,service_0,IF \
DEF:service_1=database_1.rrd:audience:MAX
CDEF:users_1=service_1,UN,0,service_1,IF \
DEF:service_2=database_2.rrd:audience:MAX
CDEF:users_2=service_2,UN,0,service_2,IF \
DEF:service_3=database_3.rrd:audience:MAX
CDEF:users_3=service_3,UN,0,service_3,IF \
DEF:service_4=database_4.rrd:audience:MAX
CDEF:users_4=service_4,UN,0,service_4,IF \
DEF:service_5=database_5.rrd:audience:MAX
CDEF:users_5=service_5,UN,0,service_5,IF \
CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
\
LINE1:aggregate_users#000000 \
VDEF:peak_users=aggregate_users,MAXIMUM \
VRULE:peak_users#0000FF COMMENT:\\n \
GPRINT:peak_users:'Peak of %.0lf users' \
GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'

OUTPUT: http://www.androidmilitia.com/rrdtool/1-week.png

/usr/bin/rrdtool graph 1-month.png --end now --start e-1m --imgformat PNG \
DEF:service_0=database_0.rrd:audience:MAX
CDEF:users_0=service_0,UN,0,service_0,IF \
DEF:service_1=database_1.rrd:audience:MAX
CDEF:users_1=service_1,UN,0,service_1,IF \
DEF:service_2=database_2.rrd:audience:MAX
CDEF:users_2=service_2,UN,0,service_2,IF \
DEF:service_3=database_3.rrd:audience:MAX
CDEF:users_3=service_3,UN,0,service_3,IF \
DEF:service_4=database_4.rrd:audience:MAX
CDEF:users_4=service_4,UN,0,service_4,IF \
DEF:service_5=database_5.rrd:audience:MAX
CDEF:users_5=service_5,UN,0,service_5,IF \
CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
\
LINE1:aggregate_users#000000 \
VDEF:peak_users=aggregate_users,MAXIMUM \
VRULE:peak_users#0000FF COMMENT:\\n \
GPRINT:peak_users:'Peak of %.0lf users' \
GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'

OUTPUT: http://www.androidmilitia.com/rrdtool/1-month.png

---------------
- Nick Harris -
---------------

On Mon, Jul 6, 2009 at 9:23 PM, Nicholas Harris <nicholas.kyle at gmail.com>wrote:

> Hello all,
>
> I've dug long and deep but I haven't found an answer to a problem I've run
> into recently (though, I am pretty new at this, so please excuse my
> ignorance).
>
> Here's the setup: I have a number of RRDs generated with the following
> command:
> '/usr/bin/rrdtool create DATABASE_NAME DS:audience:GAUGE:600:0:U
> RRA:MAX:0.5:1:105120'
>
> Each database stores the number of users in our system, and is updated
> every five minutes via Cron. Originally, I had more consolidation going on,
> but I've been cutting bits out to try and solve this issue - now I just
> store five minute snapshots over the course of a year.
>
> And here's the rub: when I try to graph out multiple RRDs together (single
> graph), the numbers do not match up for different time periods. I'll run the
> graph command for now-1day, now-1week and now-1month, and get three
> different results for each.  When I do this for one RRD at a time, I get
> consistent results (which leads me to believe something is wrong with my
> command). Multiple RRDs at the same time goes bonkers.
>
> The data is pretty limited and should show the exact same data for each
> time period. I only ran it for a small amount of time so I could compare
> numbers over different periods.
>
> Any input on this would be greatly appreciated. Here are the commands I'm
> using and sample outputs.
>
>
> COMMAND:
> /usr/bin/rrdtool graph 1-day.png --end now --start e-1d --imgformat PNG
> DEF:service_0=database_0.rrd:audience:MAX
> CDEF:users_0=service_0,UN,0,service_0,IF
> DEF:service_1=database_1.rrd:audience:MAX
> CDEF:users_1=service_1,UN,0,service_1,IF
> DEF:service_2=database_2.rrd:audience:MAX
> CDEF:users_2=service_2,UN,0,service_2,IF
> DEF:service_3=database_3.rrd:audience:MAX
> CDEF:users_3=service_3,UN,0,service_3,IF
> DEF:service_4=database_4.rrd:audience:MAX
> CDEF:users_4=service_4,UN,0,service_4,IF
> DEF:service_5=database_5.rrd:audience:MAX
> CDEF:users_5=service_5,UN,0,service_5,IF
> CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
>
> LINE1:aggregate_users#FF0000
> VDEF:peak_users=concurrent_users,MAXIMUM
> VRULE:peak_users#0000FF COMMENT:\\n
> GPRINT:peak_users:'Peak of %.0lf users'
> GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'
>
> RESULT:
> http://www.androidmilitia.com/rrdtool/1-day.png
>
>
> COMMAND:
> /usr/bin/rrdtool graph 1-week.png --end now --start e-1w --imgformat PNG
> DEF:service_0=database_0.rrd:audience:MAX
> CDEF:users_0=service_0,UN,0,service_0,IF
> DEF:service_1=database_1.rrd:audience:MAX
> CDEF:users_1=service_1,UN,0,service_1,IF
> DEF:service_2=database_2.rrd:audience:MAX
> CDEF:users_2=service_2,UN,0,service_2,IF
> DEF:service_3=database_3.rrd:audience:MAX
> CDEF:users_3=service_3,UN,0,service_3,IF
> DEF:service_4=database_4.rrd:audience:MAX
> CDEF:users_4=service_4,UN,0,service_4,IF
> DEF:service_5=database_5.rrd:audience:MAX
> CDEF:users_5=service_5,UN,0,service_5,IF
> CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
>
> LINE1:aggregate_users#FF0000
> VDEF:peak_users=concurrent_users,MAXIMUM
> VRULE:peak_users#0000FF COMMENT:\\n
> GPRINT:peak_users:'Peak of %.0lf users'
> GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'
>
> RESULT:
> http://www.androidmilitia.com/rrdtool/1-week.png
>
>
> COMMAND:
> /usr/bin/rrdtool graph 1-month.png --end now --start e-1m --imgformat PNG
> DEF:service_0=database_0.rrd:audience:MAX
> CDEF:users_0=service_0,UN,0,service_0,IF
> DEF:service_1=database_1.rrd:audience:MAX
> CDEF:users_1=service_1,UN,0,service_1,IF
> DEF:service_2=database_2.rrd:audience:MAX
> CDEF:users_2=service_2,UN,0,service_2,IF
> DEF:service_3=database_3.rrd:audience:MAX
> CDEF:users_3=service_3,UN,0,service_3,IF
> DEF:service_4=database_4.rrd:audience:MAX
> CDEF:users_4=service_4,UN,0,service_4,IF
> DEF:service_5=database_5.rrd:audience:MAX
> CDEF:users_5=service_5,UN,0,service_5,IF
> CDEF:aggregate_users=users_0,users_1,users_2,users_3,users_4,users_5,+,+,+,+,+
>
> LINE1:aggregate_users#FF0000
> VDEF:peak_users=concurrent_users,MAXIMUM
> VRULE:peak_users#0000FF COMMENT:\\n
> GPRINT:peak_users:'Peak of %.0lf users'
> GPRINT:peak_users:'%Y/%m/%d %I\:%M%p (%Z):strftime'
>
> RESULT:
> http://www.androidmilitia.com/rrdtool/1-month.png
>
>
> I also tried it on two different systems with the same results: one was
> RRDtool 1.2.23 and the other was RRDtool 1.3.7.  I've stopped updating these
> RRDs - if anyone thinks they can trouble shoot, I'd be happy to upload them.
>
>
> ---------------
> - Nick Harris -
> ---------------
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