Feb 20

Capacity ?… I Think I’ve Heard Of That… part 2

In the previous article (Capacity ?… I Think I’ve Heard Of That… part 1) we discussed the difference between capacity and performance, and where the two overlap – which is quite a lot !


In this article when companies should start to implement Capacity Management.


Firstly, let us look at the classic business cycle and discuss at what points a company should look to implement performance and capacity.

Capacity Management in the Business Cycle

* The brackets denote ‘thinking about it’, bold is ‘actively doing’


1)  Start-Up

All companies have difficult starts; how to run a business is new, your products and services no-one wants.  Those that do want to do business you’re having a hard enough time to keep happy.  Times are tough, and thinking about capacity is the last thing on your mind.  True, however, while you may be busy, now is the time to at least understand the concepts – for future reference.


2) Grow – part 1

So, you’ve got some customers.  You’re getting popular; your first computer is getting a bit ‘slow’, your spreadsheet billing system is starting to get unwieldy and don’t even talk about the broadband…  Now you remember, performance, that’s what I need !  At this stage ‘performance’ usually equates to more powerful computers, bigger disks, faster broadband.  Later this will also include application optimising.

While ‘throwing tin’ at the problem breaks all the rules of good capacity management, as it is rarely the solution, at this stage keeping the momentum in your growth is more important than ‘server sprawl’.

However, as with the ‘Start-Up‘ phase it is important to begin to understand and think about the next part of capacity management – capacity planning.


3)  Grow – part 2



4)  Saturate

You’ve been popular


So, there you have it…


The Reality

Clearly the above is an ideal.  The reality is much more difficult.  Capacity, performance and capacity management can be implemented in your company at any point.  However, the longer you leave it, the harder it will be to retro-fit into your IT function.






Jan 17

Capacity ?… I Think I’ve Heard Of That… part 1

Capacity, what is capacity ?

Well, it seems to be quite elusive; it’s normally spoken of as something we don’t have enough of, and yet when we try to measure it we seem to have too much ? How can this be ?


Perhaps a couple of definitions of capacity are pertinent[1]:

  • the maximum amount or number that can be received or contained.
  • reaching maximum capacity.


The key here is that capacity is finite, it doesn’t change.  If something can hold a maximum of 4 widgets today, it will  hold a maximum of 4 widgets tomorrow.  The only way to change the capacity is to physically change it’s size.  From our previous example, if I have 8 widgets then I need twice the capacity.  How, quickly I can use up the capacity, though, can be variable; quick or slow, steady or sporadic.  This is where performance comes in.


A definition of performance is:

  •  manner or quality of functioning[1]


That is to say performance is variable.  Think of athletes, they have good days and break World records, and bad days and come last.

To illustrated this further:

The capacity is the bucket, the performance is the tap.  If I need to fill the bucket within a certain time then it is the throughput of the tap that is key.  The bigger the tap, the quicker it fills the bucket.  The amount of water the bucket can hold, however, doesn’t change.

The same is true in IT; here the bucket is the server, the disk, the network.  How many widgets can we process, how many files can we store and how much data we can transport are capacity.  Why suddenly can we only process half the number of widgets, not write our files quickly enough or the internet is slow are more to do with performance.



[1] http://www.dictionary.com

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