Building Machine Learning Systems with Python - Richert, Coelho

Chapter 12
There are three modes of use: a reserved mode, whereby you prepay to have
cheaper per-hour access; a fixed per-hour rate; and a variable rate which depends
on the overall compute market (when there is less demand, the costs are lower;
when there is more demand, the prices go up).
For testing, you can use a single machine in the free tier. This allows you to play
around with the system, get used to the interface, and so on. However, this is a
very slow CPU machine. Thus, doing heavy computation using it is not advised.
On top of this general system, there are several types of machines available with
varying costs; from a single core to a multicore system with a lot of RAM, or even
graphical processing units (GPUs). We will later see that you can also get several
of the cheaper machines and build yourself a virtual cluster. You can also choose to
get a Linux or Windows server, with Linux being slightly cheaper. In this chapter,
we will work our examples on Linux but most of this information would be valid
for Windows machines as well.
The resources can be managed through a web interface. However, it is also possible
to do so programmatically and by setting up scripts which allocate virtual machines,
setting up disks, and all the operations that are possible through the web interface.
In fact, while the web interface changes very frequently (and some of the screenshots
that we show in the book may be out-of-date by the time it goes to the press), the
programmatic interface is more stable and the general architecture has remained
stable since the service was introduced.
Access to AWS services is performed through a traditional username/password
system, although Amazon calls the username an access key and the password a secret
key. They probably do so to keep it separate from the username/password you use
to access the web interface. In fact, you can create as many access/secret key pairs
as you wish and give them different permissions. This is helpful for a larger team
where a senior user with access to the full web panel can create other keys
for developers with less privileges.
Amazon regions
Amazon.com has several regions. These correspond to physical regions
of the world: West Coast U.S., East Coast US, several Asian locations,
a South American one, and a European one. If you will be transferring
data, it is best to keep it close to where you will be transferring to and
from. Additionally, if you are handling user information, there may be
regulatory issues if you transfer it to another jurisdiction. In that case, do
check with an informed counsel on what the implications of transferring
data about European customers to the US or vice versa are.
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