This chapter explains why you should read this book and how it can help you with any computer performance problem, now or in the future. There are so many different technologies in your transaction path; to read all the necessary books would take longer than the average corporate lifetime. What I’m about to tell you will work for any collection of computers, running any software that has ever been built. Many parts of this book help you solve the diversity and complexity problems mentioned earlier by helping you quickly determine that large chunks of your computing infrastructure are not the problem.
Your business depends on a collection of computers, software, networking equipment, and specialized devices.
You need to know the incoming workload (what the users are asking your system to do) because all computers run just fine under no load. On any given day you, as the performance person, should be able to have a fairly good idea of how much work the users are asking the system to do and what the major performance meters are showing. With rare exception I’ve found the lack of easily available workload information to be the single best predictor of how bad the situation is performance wise. The data you collect can also be used to predict the future with the other three tools in your bag: Capacity Planning, Load Testing, and Modeling.
Even though you base your projections on one peak day, you should look at the data over a period of a few days to a few weeks.
Capacity planning can show you how busy key resources are at peak load, but it can’t tell you about response time changes as the load increases.
Load tests depend on good performance monitoring to keep an eye on critical system resources as the load builds. If you need to predict a future that is different from your present, then you need to model. When your boss asks you to predict future performance of some application, first see if you can do a simple capacity plan. In a computer context, imagine your model shows that at peak load this server’s CPU is 20% busy.
This chapter shows you how to gain confidence you will make it smoothly though a projected future peak load by scaling up your current observed load.
This chapter gives you practical advice on how to load test an existing application to see if can really handle the upcoming peak.
This chapter dispels the myth of modeling complexity and shows how modeling performance can save you a lot of time and money.
This chapter teaches you how to present your results so that they are understood and are believable.


This book is concise, useful, and occasionally funny.  It gives you the tools needed to explore, and discover the hidden truths about your computing world. It shows you how to use the scientific method to decipher what they mean and how to find patterns in the raw data.
This rapidly focuses your company’s full and undivided attention on the small part of your computing world (System Z) that is causing the performance problem. If you have a good sense of what is normal for your situation, then any abnormality will jump right out at you in the same way you notice subtle changes in a loved one that a stranger would miss. Your meters should be running all the time (like bank security cameras) so that when weird things happen you have a multitude of clues to look at. Assuming you know how many guests will show up and have a reasonable understanding of what they will consume, everything you checked should be fine. The overall load starts off low and then increases in stages to the point where you achieved your goal or you fail because some resource has hit a limit and has become a bottleneck. For any test you need to know how much work you are sending into the system, the throughput and response time for the completed work, and how the system resources are responding under that load.
If your product is your website then you need to test from where your users are: all the way in and all the way back to where they live. If you only got half way to your goal before you hit a bottleneck, then every measured resource is going to be doing twice the work once you fix the current bottleneck. Imagine your workload is an even mix of Red and Blue transactions, but it is the Blue transactions that really exercise some key component of your computing world.
To use a metaphor, running a race tells you about your current aerobic capacity, not the capacity you will have after six more months of training. Everyday, in companies all over the world, regular people build simple models that answer important business questions.
If circumstances change so much that you lack confidence in that prediction, then try modeling. It doesn’t take a genius to understand that your model could be off by a lot and the server would still have plenty of CPU power left.
With it, and some work on your part, you’ll be able to solve performance problems and to walk into the CIO’s office with confidence. There are utilization meters that tell you how busy a resource is, there are count meters that count interesting events (some good, some bad), and there are duration meters that tell you how long something took.
A useful answer is: accurate enough to answer your question with a reasonable margin of safety. These patterns can tell you useful things about what’s going on inside the giant black box that is your computing world.


There are many other parts that you don’t control, can’t meter, and have no clue how they do their work.
Expected problems are no fun, but they can be foreseen and, depending on the situation, your response might be to endure them, because money is tight or because the fix might introduce too much risk.
This can save your bacon because if you spot the unexpected utilization before the peak occurs, then you have time to find and fix the problem before the system comes under a peak load.
However, even if you miss something, you are still better off having planned for reasonable amounts of the key resources. If you need more confidence in your plan, or you need to hold the response time down to a reasonable level, or if the future you are planning for includes significant changes to the transaction mix or vital systems, then you need to do either Load Testing or Modeling.
If you (and your boss) only have responsibility for a small subset of the entire transaction path then that’s all you really need to test. The closer to the utilization limit (or the projected storm track), the more precise you have to make your model. Start somewhere, collect something and, as you explore and discover, add this to your collection. Participants find a new sense of confidence in themselves an understanding  and appreciation for others that transfers over to the school and their community. You will learn impromptu wilderness medical skills (First-Aid without a kit), look for natural shelter, build a debris shelter, find safe drinking water, find resources for making primitive tools, make a primitive weapon, track wildlife, build a fire, learn back country cooking skills and what leave no trace ethics are, even forecast the weather! Learn the skills that will save your life and or your family or friends.This is a course that you won't want to missDress casual and warm.
Learn outdoor survival skills plus how to build a matchless fireBring water - snack & lunch, ID books, magnifying glass if you have them.
There was a sink and 2 toilets; no shower, no kitchen, no rooms, so the 4 of us lived in the main body of the warehouse as we built up a living space. We built up everything from scratch, and then we had a home and started the studio in the living room, this is 2011, when the business was officially registered. Just click to add your own content.You can use this page for anything you like, but we recommend focusing on one or two related topics to avoid confusing your readers.



Gain muscle lose fat calories
Grocery shopping app
Living for cheap