What is scalability?”
“Scalability, simply, is about doing what you do in a bigger way.”
– www.royans.net posted September 22, 2007
“It is the ability of a computer application or product (hardware or software) to continue to function well when it (or its context) is changed in size or volume in order to meet a user need. Typically, the re-scaling is to a larger size or volume. The re-scaling can be of the product itself (for example, a line of computer systems of different sizes in terms of storage, RAM, and so forth) or in the scalable object’s movement to a new context (for example, a new operating system).”
– definition of scalability from http://searchdatacenter.techtarget.com
What is scalability? It is potential of a computer app or product to grow.
Scalability – digitally speaking – involves two elements: the vertical and the horizontal.
With scalability, the former is easier to implement, requiring hardware rather than human “brainware.” This ease can be described with the phrase “logical singularity.” In other words, you are staying within one/the same logical unit. Let’s say, for example, that you just need more capacity for a limited number of users for this or that function. Buying another piece of equipment will often solve this problem. You are spared the need to redesign your logical architecture. No programmers, coders or engineers need to be consulted.
The mere acquisition of equipment, however, has its downside. One of them is that of limited capacity . If the number of clients for your SAAS has gone from a hundred to a million going out on a buying spree for lots of new hardware may be too expensive and inadequate as a solution to your problem. New hardware and/or equipment can cost you big, and at a certain point just won’t allow you to “scale up.” At that point you will need to “go horizontal.”
For an excellent summary/tutorial on scalability go to: http://www.royans.net/arch/what-is-scalability/