A gauge shows a single data value.
Due to its compact size, a gauge is often more effective than a graph for displaying a single data value.
Gauges identify problems in data.
A gauge usually plots one data point with an indication of whether that point falls in an acceptable or unacceptable range.
Thus, gauges are useful for showing performance against goals.
Depending on the data in the analysis, a gauge canvas might consist of multiple gauges in a gauge set.
A gauge or gauge set is displayed on a background, called the gauge canvas.
Gauges are useful for monitoring things with natural upper bounds such as:
- cpu / memory / disk size
- queue size
For example, if you create a gauge to show :
- the sales data for the last twelve months, the gauge canvas consists of twelve gauges, one for each month.
- the total sales in the US, then a gauge canvas consists of one gauge.
Counter example: a request count cannot be monitored with a gauge as they can grow without bound for the duration of an application instance’s life.
Shows data using a dial arc with one or more indicators that point to to where the data falls within predefined limits.
Shows data using a horizontal bar that changes color to indicate whether the data is within predefined limits. The inner rectangle of the horizontal bar shows the current level of data against the ranges marked on an outer rectangle.
Shows data using a vertical bar that changes color to indicate whether the data is within predefined limits. The inner rectangle of the vertical bar shows the current level of data against the ranges marked on an outer rectangle.
Shows data using a circle that changes color to indicate whether the data is within predefined limits.
Bulb gauges are useful when you need to know what the status is, and not any indication of a specific value, or relative information about other threshold ranges.