0.8.7 and 1 minute polling

denny · Joined: 24 Oct 2007 Posts: 14

Ok, I've been beating my head on this...

I'm trying to do 1 minute polling with 0.8.7. I am relatively new to cacti, had previously been using 0.8.6j. I started working on 1 minute polling a few days before 0.8.7 was released.

So, I've dumped everything and am starting afresh with 0.8.7.

I have a few questions about understanding the out of the box settings, and how to modify this for 1 minute polling operation. If you find them tiresome, please skip to the end of the post.

Out of the box, there is both a 5 minute RRA ["Daily (5 Minute Average)"] and a 1 minute RRA ["Hourly (1 Minute Average)"].

The 5 minute RRA ["Daily"] uses a step value of 1, which assuming the default polling interval of 5 minutes seems to make sense. The 1 minute RRA also uses a step value of 1, which seems to make sense if the polling interval is changed to 1 minute.

The 5 minute RRA ["Daily"] uses a timespan of 86400 [1 day], which seems to make sense. However, the 1 minute RRA ["Hourly"] uses a timespan of 14400 [4 hours], which doesn't make sense to me. Why is this?

The 5 minute RRA ["Daily"] allocates 600 rows, which assuming the default polling interval of 5 minutes would be a timespan of 50 hours. Why isn't the default number of rows for the 5 minute RRA 288 (24 hours)?

The same question applies to the rows in the "Weekly", "Monthly", and "Yearly" RRAs. They appear to allocate more than twice the number of rows needed.

The 1 minute RRA ["Hourly"] allocates 500 rows, which assuming a polling interval of 1 minute results in a timespan of 8.3 minutes. This would seem to wrap/overwrite very quickly Why wouldn't the default number of rows be 3600?

Am I just missing something basic on the math???

The timespan on the "Yearly" RRA is 33053184, which is 382.56 days. Why isn't the timespan 31536000 (or 31557600)?

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So, with all the confusing background questions out of the way, the real question is how to set the RRAs up correctly for 1 minute polling?

Ignoring the default values at install, I would have assumed this:

jacauc · Joined: 10 Sep 2006 Posts: 34

I am also very interested in this. Been struggling for days on end.
Subscribing to the thread

begemoti · Joined: 03 Apr 2007 Posts: 12

Subscribing to the thread too

denny · Joined: 24 Oct 2007 Posts: 14

With the dawn comes light

The number of rows is off by a factor of the polling interval. The minimum number of rows should be:

TheWitness · Posted: Thu Oct 25, 2007 9:03 pm Post subject:

It is good that you all perform this exercise so that in the future you understand how Tobi's excellent product works.

We have only introduced this feature in 0.8.7 as a teaser. In future releases, we will be improving things more. You can modify the values as you see fit. It's better to add new ones though. For example, I know customers that keep 5 minute data for 6 months. This makes for big RRD files, but excellent graphs.

When you all see the light, I am sure you will be satisfied with the output. In the mean time, my only recommendation is that you play on a system that can be rebuilt and then once done, move into the big time production boxes.

TheWitness

denny · Joined: 24 Oct 2007 Posts: 14

Witness, can you offer comment on how the 2x + rounding amount was chosen?

Thanks,

Denny

TheWitness · Posted: Sat Oct 27, 2007 3:41 am Post subject:

I believe it was rooted in Tobi's MRTG.

TheWitness

david(dallas) · Joined: 01 Nov 2007 Posts: 9

I upgraded from 6j to 7. Was getting 5-minutes on 6j host graphs. I upgraded, selected 1 minute internal and change cron to 1 minute.
Graphs still displaying at 5-minutes. I was trying to see if I need to select a different graph or deleting adn re-add back a host to get the 1-minute internal graphs working, but no luck so far.
I would be greatly if someone could fill me in on what I not doing after my upgrade to get the 1 minute working.

Thanks in advance..

gandalf · Posted: Thu Nov 01, 2007 12:30 pm Post subject:

Please see posts above discussing th erequired rra settings. You will at least have to change every existing rrd file to get it adjusted accordingly. Please be warned. This is no easy task. That's why we almost removed this feature from 087.
It is fine to adjust all rra's as mentioned above when doing a fresh start, deleting all existing rrd files
Reinhard

david(dallas) · Joined: 01 Nov 2007 Posts: 9

Since my last posting, I basicly did a reinstall as a new system with using no old RRA. I thought I would give that a shot. So from a fresh install, is it the casti.sql script that needs to be updated with the new rows/timespan counts shown above. Then I update sqlplus with the new data. Then when I create new host and graphs, it will start using the new numbers?

david(dallas) · Joined: 01 Nov 2007 Posts: 9

I might have figured out what you meant now, but still graphing at 5 minutes. I did update the Data Sources - RRA's to match the above numbers in Denny's last posting..

Name Steps Rows Timespan**
Hourly (1 Minute Average) 1 60 3600
Daily (5 Minute Average) 5 288 86400
Weekly (30 Minute Average) 30 336 604800
Monthly (2 Hour Average) 120 372 2678400
Yearly (1 Day Average) 1440 366 31557600

david(dallas) · Joined: 01 Nov 2007 Posts: 9

Data Sources Poller interval still shows 5 minutes even though I changed Settings -> Poller -> Interval -> 1 minute. Are these 2 different things?

Name** Data Input Method Poller Interval Active Template Name
srvalph2-um1 - CPU Usage - Nice Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - Nice
srvalph2-um1 - CPU Usage - System Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - System
srvalph2-um1 - CPU Usage - User Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - User
srvalph4 -dm1 - CPU Usage - Nice Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - Nice
srvalph4 -dm1 - CPU Usage - System Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - System
srvalph4 -dm1 - CPU Usage - User Get SNMP Data 5 Minutes Yes ucd/net - CPU Usage - User

gandalf · Posted: Fri Nov 02, 2007 5:18 am Post subject:

denny · Joined: 24 Oct 2007 Posts: 14

For those of you who are interested, the following is what I ended up with:

david(dallas) · Joined: 01 Nov 2007 Posts: 9

I have changed the rrd per postings, change the cron to 1 minutes and change the settings interval to 1 minute, but yet I continue to get displays at 5-minute intervals. TOTALLY AT A LOSS...