MRTG 3

DRAFT (!!!!) by Tobi Oetiker, 2006-08-22, v2

Use Cases

Automated Discovery
When MRTG gets started, it will discover the network and start moniting the devices it finds.
Device Database
If information about the devices to be monitored are available in a database, this information can be used by mrtg to define its workload.
Device Knowledge
When MRTG detects the type of device it is monitoring, it tries to read a device config file for more information.
Extensions
Functional extensions can be realised as plugins. Plugins are perl modules that can inherit functionality from existing plugins.
Presentation
Data is presented in a webinterface where it can be organised according to differnt properties like type of data, type of device, location, organisational structure, imporance.
Low Latency
Polling data from remote devices is a high latency affair. By running probes in parallel, this task gets faster.

Components

Inventory

Takes care of figuring out what objets are available for monitoring.

mrtg2_cfg_reader
reads an mrtg2 config file to figure out which devices were being monitored.
database_reader
polls a SQL database for information about devices
nmapper
runns nmap or a similar tool to figure out who is present on the network
snmp_discovery
uses snmp figure out what devices are on the network and also what sortof information they can provide.

The inventory will be kept current as mrtg runs.

Poller

Gets the actual monitoring data off the devices.

pinger
send pings to devices to measure latency
snmpbulkget
pull blocks of data off snmp capable devices

expecter
execute an external program under perl-expect control to get some data back.
rstat
use rstat to query hosts abouttheir load and users

Storage

The storage modules use information from the inventory to determine what data should be stored and instruct the pollers to get it for them.

latency
store latency measurements
network-if
store networkinterface data
host
store information on a hosts memory, kerel and cpu status
disks
store information about disk fill state

Graphing

Modules that take the stored infomation and turn it into neat graphs

mrtg_classic
produce a graph that thries to look like the thing that mrtg-2 did
smokeping
create a smokeping graph
host
graph depicting the state of a host
disk
graph for disks
cluster_state
take information from many hosts and create an overview graph

Presentation

Modules that organize the data for presentation. They call upon the graphing modules to produce the graphs.

network_topology
present information according to the network topology.
information_type
organize by the type of information
graph_interest
sort the graphs by 'interest'

There is also a way to define the template for the look and feel of the web interface.

Rating

The rating plugins decide how interesting a graph is from 0 to 100. This allows to display interesting graphs 'on top' and also to send alarms once a graph gets a sufficiently high rating.

latency
is there a 'unexpected' change in latency.
threshold
check data for threshold, based on local rules or on information acquired by an inventory module.

Architecture

The mrtg daemon will use forking to reduce latency. The forked instances will do the polling and once the information is received also the storing. For improved performance, the storing could also be off loaded to a writer process that caches data and does bulk-updates to the rrds. There must be a way for the webinterface to partially flush the cache before drawing a graph.

Open Questions

Some plugins depend heavily on others in order to function, there must be some standard way for them to communicate configuration information.

Sponsors

Last modified 9 years ago Last modified on May 10, 2013, 12:22:18 PM
 

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