Information Technology Reference
In-Depth Information
Terms to Know
QPS:
Queries per second. Usually how many web hits or API calls received per
second.
Active Users:
The number of users who have accessed the service in the speci-
fied timeframe.
MAU:
Monthly active users. The number of users who have accessed the service
in the last month.
Engagement:
How many times on average an active user performs a particular
transaction.
Primary Resource:
The one system-level resource that is the main limiting
factor for the service.
Capacity Limit:
The point at which performance starts to degrade rapidly or be-
come unpredictable.
Core Driver:
A factor that strongly drives demand for a primary resource.
Time Series:
A sequence of data points measured at equally spaced time inter-
vals. For example, data from monitoring systems.
18.1 Standard Capacity Planning
Capacity planning needs to provide answers to two questions: What are you going to need
to buy in the coming year? and When are you going to need to buy it? To answer those
questions, you need to know the following information:
•
Current Usage:
Which components can influence service capacity? How much of
each do you use at the moment?
•
Normal Growth:
What is the expected growth rate of the service, without the in-
fluence of any specific business or marketing events? Sometimes this is called
or-
ganic growth
.
•
Planned Growth:
Which business or marketing events are planned, when will
they occur, and what is the anticipated growth due to each of these events?
•
Headroom:
Which kind of short-term usage spikes does your service encounter?
Are there any particular events in the coming year, such as the Olympics or an
election, that are expected to cause a usage spike? How much spare capacity do
you need to handle these spikes gracefully? Headroom is usually specified as a
percentage of current capacity.
Search WWH ::
Custom Search