What does scalability mean to you?
architecture, scalability
Solution
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.
Problem
I posted a similar question on how scalable linq is. There were so many different views on what scalability actually meant in some recent conversations, so it has sparked me to ask this question as well. What does scalability mean to you?