What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general.

Learn more

PRTG Network Monitor

Intuitive to Use. Easy to manage.
More than 500,000 users rely on Paessler PRTG every day. Find out how you can reduce cost, increase QoS and ease planning, as well.

Free Download

Top Tags

View all Tags

SNMP Linux Meminfo sensor: Problem w/ memory buffers/cache



I just installed an SNMP Linux Meminfo sensor for a Linux server running RHEL 7.1. The sensor reports an error with available memory:

Percent Available Memory: 1% Available Memory: 34 MByte Physical Free Percent: 95 % Physical Free: 3,501 MByte Swap Used Percent: 100 % Swap Free: 3,984 MByte Total Used Percent: 97 % Total Free: 7,485 MByte

The problem is the Available Memory (34 MB) and % Available Memory (<1%). But in Linux, of course, "free" memory is not what it seems, because the memory in buffers and cache is available to be used:

total used free shared buff/cache available Mem: 3786048 111776 32172 57900 3642100 3563862

The channels I care about are the Physical Memory channels. For now I have disabled limits for the Available Memory channels, and this has stopped the alerts. But since I can't delete channels, is there something I can do to get the meminfo sensor to account for memory in buffers and cache?

meminfo memory snmp

Created on May 1, 2015 6:55:17 PM

2 Replies



this would not be possible with the SNMP Disk Free Sensor but with an SNMP Library Sensor. When creating the same, please choose the Basic Linux Library. In the following screen you are able to choose from several available memory counters which include mem free, buffered and cached.
Best regards

Created on May 5, 2015 11:30:34 AM by  Konstantin Wolff [Paessler Support]



Thanks, that works well, and may be what we use in the future.

The only drawback is that having separate memory counters chews up more sensor licenses than a single sensor with multiple channels, but I'll learn to live with that. :-)

Created on May 5, 2015 8:10:40 PM

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.