Formulas - Definition and application

Products

VMware Smart Assurance

Issue/Introduction

How to apply a formula in Watch4Net?
What is a Watch4net formula and how do I apply it?

Environment

Watch4Net/M&R - 7.x

Resolution

Broadly defined, a formula is a way to manipulate and transform data. More specifically, a formula is the definition of a specific operation independently of the context that can be applied to data, such as applying a formula that calculates BandwithUtilization. Formulas enable complex computations on any number of metrics, and can be applied on any node of the tree. The Formula section allows the application or removal of already existing formulas to the currently edited node.

Adding new formulas:
- New formulas can be applied through the Add another Formula button. Use simple clicks to navigate through the Formula browser, then select the formula to apply and click ok. Once done, the newly applied formula will appear in the panel, but with default parameters, settings and results which need to be modified for your environment, especially the parameters. When ready, you must click the Apply Changes button for the changes to be saved. More details about applying formulas are described in the following sections.

Removing applied formulas:
- In order to remove an applied formula, simply hit the red "X" at the right of its name. Note that such a removal is automatically saved upon confirmation.

Formulas Application Concept:
- Several formulas can be used at different levels to modify the metrics values. In that way, you have to keep in mind this expression: "from the leaves to the root"
- This means you have to begin the calculation at the deeper node to then back to the root. For instance, let s say you want to see the result of this formula : (Availability * 20) / 30. We can see that there are 2 formulas to apply : Multiplication and Division. The first formula to apply is the multiplication. Then, the division formula grabs the multiplication result (from the leaves to the root concept) and does the division calculation.

Applying an Watch4net Formula
To apply a formula in Watch4net:

Go to Edit Mode and click on the Formula tab.
Select your report that needs a formula.
Click to the Add another formula button and select your formula.
Select the parameters, fill formula settings and set the result. See following "Formula input parameters" section.
Click on Apply Changes to validate your formula.

Formula input parameters
You have the following options of managing input parameters:
- Filter on this node : A basic Watch4net filter. For instance : name='Availability'
- Child formula result : Get the child formula result (From the leaves to the root concept)
- Constant value : Constant float value. For instance: 3.0
- Property Value : Watch4net property must be filled here. For instance: ifspeed
- Combined parameters : Combined several type of input parameters. For instance a filter on this node parameter and a constant value parameter
- Empty parameter : Leave empty the input parameter
  
  Example
  For example, you could use the following types of parameters :
  
  Multiplication formula => Filter on this node : name=Availability and Constant value : 20
  Division formula => Child Formula Result : Multiplication Result and Constant Value : 30

Additional Information

FAQs:

Q: Where can I apply formulas?
A: On every Watch4net report.

Q: How is an Formula composed?
A: A Formula is composed of the following:

Parameters: Indicators or Properties. Values over an interval of time, with a period subjected to a Formula.
Settings: Constant values. Constant provided to a Formula as soon as it's initialized, and may depend on context (dynamic value).
Results: Value returned by the formula. Values over an interval of time, with a period generated by a Formula.

Q: What are the formulas already bundled with Watch4net?
A: A lot of formulas such as maths, forecasting, availability and SLA, thresholds, utilization, etc. A formula is the definition of a specific operation that can be applied data. So it is a way to manipulate and transform data. For instance, we can apply a formula that calculates BandwithUtilization. Watch4net includes the following formulas that you can add/create or edit with the formula editor:

Availability: spatial.AggregationOfTemporalAggregation, spatial.Average , spatial.Max, spatial.MaxOfTemporalAverage, spatial.Min, spatial.Percentile, spatial.QuadriPercentiles, spatial.ScaledChildCount, spatial.Sum, temporal.AggregationOfAggregation, temporal.BaseLine, temporal.Percentile, temporal.TimeRangeAggregation, Absolute, Addition, Delta, DifferentialRatio, Division, MultiPercentage, Multiplication, Percentage, PercentageIncrease, Ratio, Scale, SpatialMin, Subtraction
Forecasting: ExponentialSmoothing, ExponentialTrending, LinearForecast, PeriodicExponentialTrending & PolynomialForecast
Math: Absolute, Addition, Delta, DifferentialRatio, Division, MultiPercentage, Multiplication, Percentage, PercentageIncrease, Ratio, Scale, SpatialMin, Subtraction
Sla: AvailabilitySla, CompareMetricToObjective
Threshold: DevicePercentage, OverThreshold, OverThresholdCount, SustainedThreshold, ThresholdWindow
Util: AverageOnCustomPeriod, BoundaryFormula, ChildCount, Conditional, ConditionalMetricValueCount, ConditionalTimeValueCount, ConditionalValue, ConvertToPercentage, NodeMaintenancePeriod, Nop, Nop4, ReplaceValue, SimpleConditionalValue
Utilization: BandwidthUtilization, BusyHourFormula, MosAndRFactor, PacketRate, PacketRateHC, PacketSize, PacketSizeHC, RateToVolume, StorageUtilization, UtilizationDetection