Re: scalability and manageability
On 1/20/2011 10:21 AM, Daniele Futtorovic wrote:
On 20/01/2011 09:35, Patricia Shanahan allegedly wrote:
The real issue is the right set of tiers for the
application.
If you get that right, manageability and scalability will both increase.
The essence of modularization as a strategy for building complex systems
is the fact that managing n simple subsystems plus some simple
interactions between them is often easier than managing one system that
does their combined function. Adding tiers, if they are the right tiers,
can improve manageability.
On the other hand, increasing the number of tiers for the sake of doing
so, on the assumption that it will automatically increase scalability,
can have the effect of reducing scalability. Even when tiers are run on
the same hardware, communication between them tends to be more expensive
than intra-tier communication. With a bad tier design, the inter-tier
communication can be the limiting factor for scalability.
A quick inquiry if I may. In the general (IT) parlance, is the term
"scalability" used in the sense of both high and low-end scalability, or
only high-end?
For increasing tiers certainly doesn't increase low-end scalability. It
might not decrease it, but I can't really imagine how it could increase
it (as generally every tier will have a minimum "cost" attached to it).
df.
My understanding of scalability is specific to increases in size of
system and workload. I don't know what you mean by "low-end scalability"
unless you are using "scalability" as a synonym for performance.
Scalability is not the only important performance issue. For example, in
some systems, response time under light load may be more important.
Patricia