Chapter 11. Templates

Figure 11 2. Adding a Data Template

11.2.1.1. Data Source Items

Like a graph, a data source can have more than one items. This is useful in situations where a script returns more than

piece of data at one time. This also applies to data queries, so you can have a single data template that contains both

inbound and outbound traffic, rather than having to create a separate data template for each.

Table 11 5. Field Description: Data Source Items

Name

Description

Internal Data Source Name This is the name used by

RRDTool

to identify this particular data source within the

RRD file.

RRDTool

places a limit of 19 alphanumeric characters (plus '_' and ' ') on this

field.

Minimum Value

Here is where you specify the minimum value that is expected for this data source in

the RRD file. If a value lower than the minimum is given, it will be stored as Unknown

(U).

Maximum Value

Here is where you specify the maximum value that is expected for this data source in

the RRD file. If a value higher than the maximum is given, it will be stored as

Unknown (U).

Data Source Type

There are four types of data that

RRDTool

can represent for any given data source:

COUNTER, GAUGE, ABSOLUTE, and DERIVE. A gauge is for numbers that are not

continuously incrementing. A counter is for continuously incrementing values that

might overflow, while a derive does not overflow. The absolute type is used for

counters that are reset upon reading.

Heartbeat

As defined by

RRDTool

:  The maximum amount of time that can pass before data is

entered as "unknown". This field is usually '600' or 2 data gathering intervals .

11.2.1.2. Custom Data

Assuming you selected a data input source on the previous screen, you should now be presented with a Custom Data

box. Each custom data field is per field templatable as all of the other data source fields are. Even if you select the Use

Per Data Source Value checkbox, it might be useful to specify a value that will be used as an "inital value" for any data

source using this data template.

11.2.2. Applying Data Templates to Data Sources

Applying a data template to a data source is a very simple process. The first thing you must do is select the data source

you want to apply the template to under Data Sources. Under the Data Template Selection box, select the data template

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