RRA Settings for 10s Polling and No Data Loss

[KyleT]

Hi All

We finally got a Cacti server built just for 10s polling several interfaces. Heaps better than 5 minutes mind you!

However, after a few hours I have stumbled into a problem. The Daily, Weekly, Fortnightly, and Monthly RRAs I defined are no longer drawing. I can now only see the 4 Hourly! I noticed they slowly die after time.

4 Hourly (10s Average)
Consolidation Functions: Average
X-Files Factor: 0.5
Steps: 1 (No consolidation)
Timespan: 14400 (1 hrs)
Rows: 1440 (1 hour and 360 data points per hour)

Daily (10s Average)
Consolidation Functions: Average
X-Files Factor: 0.5
Steps: 1 (No consolidation)
Timespan: 86400 (24 hrs)
Rows : 8640 (1 days with 24 hours and 360 data points per hour)

Weekly (10s Average)
Consolidation Functions: Average
X-Files Factor: 0.5
Steps: 1 (No consolidation)
Timespan: 604800 (7 days)
Rows: 60480 (7 days with 24 hours per day and 360 data points per hour)

Monthly (10s Average)
Consolidation Functions: Average
X-Files Factor: 0.5
Steps: 1 (No consolidation)
Timespan: 2678400 (31 days)
Rows: 267840 (31 days with 24 hours per day and 360 data points per hour)

Yearly (10s Average)
Consolidation Functions: Average
X-Files Factor: 0.5
Steps: 1 (No consolidation)
Timespan: 31536000 (365 days)
Rows : 3153600 (365 days with 24 hours per day and 360 data points per hour)

Can anyone see any mistakes I made in the RRA definitions?

Now the really odd thing is, this does not happen on my Load Average or Memory Usage graphs. All graphs are drawing for them...

Cheers
Kyle

[gandalf]

4 Hourly (10s Average)
Steps: 1 (No consolidation)
Daily (10s Average)
Steps: 1 (No consolidation)
Weekly (10s Average)
Steps: 1 (No consolidation)
Monthly (10s Average)
Steps: 1 (No consolidation)
Yearly (10s Average)
Steps: 1 (No consolidation)

Those steps make no sense.
Either only keep the last one as it covers all others
or
Use consolidation (recommended).
Furthermore, I urge you to consider using MAX consolidation function instead of AVERAGE (ok, when using step=1 there's no difference at all).

R.

[KyleT]

Thanks for your reply.

I'm using Average as the consolidation function as that is what is used in the No Data Loss guide: http://docs.cacti.net/manual:088:8_rrdtool.03_big_rra

Is is possible to have one RRA (the yearly one) but then specify several views for it? I want to have the 4 Hourly, Daily, etc views available without zooming on the yearly one.

Regards
Kyle

[KyleT]

Hmmmm I think I just worked it out.

It wasn't the RRAs that were stopping the graph from drawing, it was a comment that I put on all the graphs to show the total amount transferred:

Code: Select all

|sum:auto:current:2:auto|

The following link explains the usage of this Bandwidth Summation
http://docs.cacti.net/manual:087:6_reference.variables

After playing around, I determined the following:

|sum:auto:current:2:84360| - Works.
|sum:auto:current:2:84361| - Does not work.

All I changed was the timespan that the calculation was run on. Basically it seems 8364 PDPs/RRA rows is the limit (84360 / 10 = 8364 as I'm using 10s polling).

Could a dev please comment whether this is by design, or a bug?

[gandalf]

|sum:auto:current:2:84360| - Works.
|sum:auto:current:2:84361| - Does not work.

All I changed was the timespan that the calculation was run on. Basically it seems 8364 PDPs/RRA rows is the limit (84360 / 10 = 8364 as I'm using 10s polling).

Could a dev please comment whether this is by design, or a bug?

This is Tony's stuff, I suppose. PM him at user rony
R.

[rony]

Check you apache error log. You are probally running out of memory.

[KyleT]

Check you apache error log. You are probally running out of memory.

Seems you are right Tony.

Code: Select all

[Tue Mar 16 10:43:39 2010] [error] [client 10.254.101.137] PHP Fatal error:  Allowed memory size of 16777216 bytes exhausted (tried to allocate 71 bytes) in /usr/share/cacti/lib/rrd.php on line 504, referer: http://cactirealtime/cacti/graph.php?action=view&rra_id=all&local_graph_id=49759
[Tue Mar 16 10:43:39 2010] [error] [client 10.254.101.137] PHP Fatal error:  Allowed memory size of 16777216 bytes exhausted (tried to allocate 47 bytes) in /usr/share/cacti/lib/rrd.php on line 496, referer: http://cactirealtime/cacti/graph.php?action=view&rra_id=all&local_graph_id=49759
[Tue Mar 16 10:43:40 2010] [error] [client 10.254.101.137] PHP Fatal error:  Allowed memory size of 16777216 bytes exhausted (tried to allocate 4097 bytes) in /usr/share/cacti/lib/rrd.php on line 170, referer: http://cactirealtime/cacti/graph.php?action=view&rra_id=all&local_graph_id=49759
[Tue Mar 16 10:43:40 2010] [error] [client 10.254.101.137] PHP Fatal error:  Allowed memory size of 16777216 bytes exhausted (tried to allocate 13 bytes) in /usr/share/cacti/lib/rrd.php on line 496, referer: http://cactirealtime/cacti/graph.php?action=view&rra_id=all&local_graph_id=49759

I might try increasing the max memory in php.

Thanks for your assistance!
Kyle