Downloads

This section contains resources produced by Capacitas as part of our programme to support and promote performance and capacity management across the ICT industry.

Capacitas Excel Add-In

A Microsoft Excel Add-In to support analytical modelling of ICT systems using Excel worksheet functions.

The Capacitas Excel Add-In contains the following four worksheet functions:

• An Erlang C function to estimate the probability that all of a number of servers are busy at a given average load per server
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/M/N queuing model
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/G/1 queuing model
• A function to estimate response times (either with or without service time) for a system that may be approximated by an M/G/N queuing model

The use of these functions and the principles behind analytical modelling are described in detail in the Capacity Planning: Tools and Methods training course.

Contents

capacitas.zip contains the following files

• CAPACITAS.xla - the Excel Add-In
• Examples.xls - an Excel spreadsheet that describes the use of each function, along with an example
• licence.txt - the licence agreement

Installation Instructions

Follow these steps to download and install the Capacitas Excel Add-In:

• Click on capacitas.zip to download the Add-In
• Unzip and save CAPACITAS.xla into the appropriate Add-Ins directory (for example, C:\Program Files\Microsoft Office\Office\Library)
• Start Microsoft Excel
• Select 'Add-Ins...' from the 'Tools' menu
• Check the 'Capacitas' checkbox (If the Capacitas Add-In does not appear; click the 'Browse...' button, manually locate capacitas.xla and click 'OK')
• Click 'OK'

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