What does scalability mean to you? [closed]

Answer 1

I look at scalability from two perspectives:

Scaling Up

If I add more RAM to the box that something is running on, how much additional performance and capacity do I gain? If one application I have can handle 300 more connections and runs 15% faster when I add 2 GB of RAM to my server and another application can only handle 100 more connections and runs 5% faster, application A is clearly more scalable.

Scaling Out

Now, if I add more boxes to my set up, how much additional performance and capacity do I gain? Can I set up web front ends to handle more client traffic? If so, is there a linear increase? If I add 3 boxes, can I get 3x more users accessing my site? Can I add more databases to distribute the data load? Can I scale up multithreading? If I can easily add a machine to my network to add capacity to my application, then it is scalable.

This, by the way, is one of the primary drives of n-tier.

Answer 2

Scalability - The ability of a system to use additional resources to achieve increased capacity or throughput. Additional resources such as drives, memory, network cards, processors, or machines.

I don't directly associate scalability with feature growth, although adding features to a system at its scale limit may not be possible.

Answer 3

I answered that question as if you meant fast, but that's because I didn't want to be a jerk :) -- meaning, I didn't want to start a discussion about what scalable means. I think of scalable as: adding resources to the system increases its performance.

In that sense, PLINQ is scalable, because adding more cores will make it run faster.

Answer 4

Scalability means the ability to handle growth in either of these 2 areas:

1) Ease of adding new features, fixing bugs. To make the code do these new things how hard is it to do? While this may be maintainability in some ways, it is also the question of whether you can build the code to handle a bigger scale easily.

2) Ability to handle greater and greater load which may be multiple requests simultaneously in Web Development or larger datasets for a simple Database-driven website, e.g. could you make an application that handles tables with hundreds of thousands of rows that is still viewed as "quick"?

Generally for me scalability means the ability to grow.

Answer 5

I think of scalability as a measure of the smoothness of the cost-performance curve.

That is, if you can spend a little on computing resources and get a low performance system, and gradually adding resources you can get a proportionally better system, it's scalable. If you have to add resources in expensive chunks, to get less than linear improvements, it's not scalable.

Answer 6

Woh!, big word....

I define it a-new every project, because it depends on what the client wants.

Scalability isn't always about adding processing/storage capacity, but can include the support of many inputs and many outputs as well.