Extract:

Every system administrator knows the situation: The load on the servers increases, the data traffic plugs the network interface card. As at first sight there is no reason for this, only a look behind helps: Often only then problems can be isolated and traced.

If a server grinds to a halt, there are different opinions about the reason for it. Often the different point of views of colleagues and the information which the admnistrator finds in the internet are confusing. In contrast, tools for long-term monitoring, which record and graphically illustrate data over long time periods give important information. For this monitoring and archiving functions mostly the comprehensive software library Rrdtool is used in the open source field. As webfronted Cacti automatises the Rrdtool measurements and provides a comfortable and intuitive user interface.

Round Robin Databases

RRD, the acronym for Round Robin Database, stands for a concept, which efficiently archives sensor data measured over a long time period. Therby it is important to reduce the data amount to a reasonable quantity, without losing important information: It is not so important, how much the temperature was in the server box in the last month to a certain time. But much more important is the average or maximum temperature during the week. In contrast for the temperature of today there are shorter periods relevant. This is where the concept of Round Robin Archive puts on.

You can find the hole article in the Linux Technical Review, issue 02 - Monitoring, or sent us an email.