Intermittent gaps in graphs on some devices most work


I have a redistributed system that I have some odd problems with.
Some machines are polling flawlessly independent where it’s placed. Some are not that flawlessly.
I have alot of gaps in some graphs (always same device) independent in what poller-group i put it in.
The pollers arent reporting any problem with reaching the device and it always works when I manually do the polling.
I’ve tried removing all devices and just use the standard setup, without any changes. Today i added about 500 devices that graph (49k ports working maybe about 500 ports that have holes) just as it should do, but this device that were added in the beginning doesnt graph.


CPU graph

As images show its not really conclusive that it is a reachablitity issue, but rather a response/graph-issue?

Right now i use 2 pollers in this group with dispatcher service.
All machines are placed on NVME servers with very load.
MariaDB: 0.23, 0.32, 0.35
RRDcached: 0.34, 0.29, 0.21
Web/Cluster Master: 0.00, 0.02, 0.03

I have no strange lines in journal on either machine.

Anyone having any idea of what can cause this?
Anyone having any idea of how i can resolve this or lead me in a way I can troubleshoot it?

The odd thing for me is that the new devices doesnt have this issue, only the first ones. As I wrote this post i actually removed one of the troubled devices, removed the RRD’s and added the device again, to see if it could be a creation problem from the beginning.

All systems are up to date as below and the issue has been since i newly installed it 2 weeks ago.


Component Version
LibreNMS 23.11.0-28-ge77a9ccf8 (2023-12-13T11:08:42+01:00)
DB Schema 2023_11_21_172239_increase_vminfo.vmwvmguestos_column_length (274)
PHP 8.1.2-1ubuntu2.14
Python 3.10.12
Database MariaDB 10.6.12-MariaDB-0ubuntu0.22.04.1
RRDTool 1.7.2
SNMP 5.9.1

[OK] Composer Version: 2.6.6
[OK] Dependencies up-to-date.
[OK] Database connection successful
[OK] Database Schema is current
[OK] SQL Server meets minimum requirements
[OK] lower_case_table_names is enabled
[OK] MySQL engine is optimal
[OK] Database and column collations are correct
[OK] Database schema correct
[OK] MySQl and PHP time match
[OK] Distributed Polling setting is enabled globally
[OK] Connected to rrdcached
[OK] Active pollers found
[OK] Dispatcher Service is enabled
[OK] Locks are functional
[OK] Python wrapper cron entry is not present
[OK] Redis is functional
[OK] rrdtool version ok
[OK] Connected to rrdcached

what does your poller stats look like?

do you see anything interesting in /device/device=1/tab=graphs/group=poller/ Poller Modules Performance etc for the problematic ports/devices?

or the logs for those devices → /device/1/logs

have tried to move it to poller group 1 aswell without any success. (This is after i added 500 devices spread on the pollergroups, so the time has been lower before)

Device pollerstats:

Eventlog for the device: Shows from the 12th to the 14th, the graph errors i posted were from the 13th (CEST)

So as you can see there are nothing visible.
BUT! I deleted one device (and cleared the rrds) and just cleared the rrd’s for another device and they seem to be graphing as they should.
So somewhere i think it must be because a partially corrupt RRD-file, can I be correct with that statement?

Doesn’t look too bad. If your load on your pollers is low-ish and you have enough CPU cycles/cores I would change the poller workers to 16 instead of 8 on the first two and restart them and see if that improves things.

It doesn’t take much (a small rise in latency) to push polling times up a little which would exceed the number of available/maximum worker seconds available …

As i’ve written before. I have had this problem with fewer devices aswell.
The problem just didnt occur after 15.00 yesterday, its been like that for 2 weeks, so the load on the pollers isnt related, its even better after 15.00 so the load isnt impacting it negativly at all, rather positivly, since it have less gaps than before.



see how many SQL connections you have, and up the default from the (i think 100) to like 500.

this fixed my gap issue.

added to:

Sadly no, I solved the issue with removing the RRD-files and let it run further, and all graphs are without any gaps anymore.