Cacti (home)ForumsDocumentation
Cacti: offical forums and support
It is currently Mon Jun 17, 2019 2:35 am

All times are UTC - 5 hours




Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: [SOLVED] CACTI vs. poller interval vs. rrd preset vs. cron
PostPosted: Mon Apr 08, 2019 10:17 am 
Offline
Cacti User

Joined: Mon Oct 01, 2018 10:09 am
Posts: 122
Hello All,

I have a basic question on the relationship between the rrd data profile (aka preset)
the poller interval (I am using spine), and the cron interval.

I was able to eliminate all poller table not empty warnings by deleting all the rrd files (I have 421 devices.
I did this by choosing the System Default preset, using 5 min for cron poller run, and 5 minute for poller/spine run.

This created rrds, graphs without gaps, and stats are all green.

I assumed that when the poller is run (spine based, using 6 processes and 10 threads) it writes to the rrd
file(s) every 5 minutes. I figured that now I have good rrd files and graphs set, that I should be able
to change the poller interval (not cron) to 1 minute, thinking that instead of updating rrd files every 5 minutes,
it would just update the rrd file(s) every minute since the rrd profile remained unchanged. cron was unchanged, running
every 5 min.

I figured wrong! As soon as I changed the poller to 1 minute, and rebuilded the cache, I started getting "poller output table not empty"
warnings. When I changed the poller interval back to 5 minutes, all warnings went away.

Am I missing something here? I did try setting cron to every minute, but that still gave poller table warnings, etc.

I am open to any suggestions,

Thanks,
eholz1


Last edited by eholz1 on Tue May 07, 2019 6:15 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Cacti poller vs. poller interval vs. rrd preset vs. cron
PostPosted: Mon Apr 15, 2019 7:22 am 
Offline
Cacti Guru User

Joined: Sun Aug 27, 2017 12:05 am
Posts: 2499
You can't just update the profile to 1 minute because the RRD's contain a STEP which matches. You can't just change the RRD's STEP either because it has no idea what to do about the missing data or what data to summarise if less is needed.

For example, in your case, you are dropping from 5 minute (300 second) steps to 1 minute (60 second) steps. This means that for each step, there are four missing ones.

There is a script one of our guys was testing that allowed for adjustment of the steps, but that is currently being reviewed. It basically tries to fill in the missing data with an existing value. Not ideal but the best that it can do.

_________________
Official Cacti Developer

Cacti Resources:
Cacti Website (including releases)
Cacti Issues
Cacti Development Releases
Cacti Development Documentation

My resources:
How to submit Pull Requests
Development Wiki and How To's
Updated NetSNMP Memory template for Cacti 1.x
Cisco SFP template for Cacti 0.8.8


Top
 Profile  
 
 Post subject: Re: Cacti poller vs. poller interval vs. rrd preset vs. cron
PostPosted: Mon Apr 15, 2019 10:19 am 
Offline
Cacti User

Joined: Mon Oct 01, 2018 10:09 am
Posts: 122
Hello netniV,

Excellent - actually, I am not sure I, as a user, would want to have a script that would
re-set the step - I also notice that the rrdtool "step" change does not work to change the step either.

It seems there are currently just two ways to change the step for an rrd of a given profile:
use a different profile (like 1 minute), see what the debug code puts out for the datasource,
and delete old or overwrite existing rrd file with the new step value using the new code (for one device),
OR - change the profile for an interface template, and delete all the rrd files for the device(s), and let them
rebuild.

Downside to deleting all, is data in file for previous step value is lost.

I found a workaround that gives me the capability to select the profile/preset by checking the box for the
Data Source Profile in a given data source template that allows overriding the default profile for that interface.

At least for me, I have discovered that I need to "plan ahead" if I want to use a profile other than "System Default" i.e.
is there any benefit to using the "High Collection Rate" profile, etc.

Thanks for reply,

eholz1


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

Protected by Anti-Spam ACP Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group