Universal Scalability Law Modeling Workbook


This Excel workbook is a rapid way to model and understand your systems' practical scalability limits, using Dr. Neil J. Gunther's Universal Scalability Law. This model helps you determine how much crosstalk and serialization (queueing) affect your systems' performance under increasing load.

Baron Schwartz provides a walkthrough of the best ways to use the USL Workbook in the video below:

Conventional ways to determine system capacity are often difficult, expensive, and don’t give results you can really believe in.

  • You can set up load tests, but it takes a lot of work and time, and the results are suspect because the workload is always artificial in some way. 
  • You can also run benchmarks, but most benchmarks are pretty useless for predicting a system’s usable capacity. 
  • Another way to predict system capacity is with queueing theory, using the Erlang C formula to predict response time at a given utilization. Unfortunately, this requires that you know service times, which are often impossible to obtain.

If load tests, benchmarks, and queueing theory are difficult to use, can the USL help? Yes, it can. Because the USL is a model, it can help you predict how a system will perform under load beyond what you can observe. 

Submit the form below to download the workbook and use it for convenient scalability modeling!