System Administration - eXist: A NoSQL Database and Application Development Platform - page 409

(or EC2 , as it is better known) is a cloud computing platform where virtual machines
can easily be created and destroyed.
EC2 supports a wide choice of operating systems, including Solaris, various Linux
distributions (including EC2's own Amazon Linux), FreeBSD, NetBSD, and Win‐
dows. Amazon EC2 virtual machine instances are created from Amazon machine
images (AMIs), which contain the operating system and any preinstalled software. A
wide variety of AMIs are available from the AWS Marketplace . The cost of running a
virtual machine on EC2 is typically calculated by the hour and depends on four main
factors:
Instance sizing
Amazon offers a variety of virtual machine instance sizes. Some are optimized
for CPU processing, others for large memory use, and still others for storage and
I/O performance. Which to use with eXist will depend entirely on your use of
eXist, the database size, and the queries that you are performing. It is entirely fea‐
sible with EC2 to start on one type of instance, and then at a later stage create an
image of your virtual machine and migrate to a larger or smaller instance as
necessary.
Instance location
Amazon has several data centers located in the US, South America, Europe, and
Asia. Amazon charges differently depending on which data center you wish to
run your instance in. The cheapest data center is usually on the East Coast of the
US, but it may make more sense to locate your servers closer to your customers
to reduce latency, or you may be required to stay within a political region to
comply with governmental data protection laws.
On-demand or reserved instances
If you are running servers on EC2 for production purposes or over a longer time
frame than a few weeks, it could be cheaper to prepurchase reserved CPU com‐
pute hours rather than paying EC2's on-demand rate.
Software
Depending on the AMI that you choose to use to create your virtual machine
instance, there may be an extra cost associated with provided and/or preconfig‐
ured software packages.
One of the nice things about EC2 is that it provides a free tier. If you qualify, then the
free tier gives you access to a micro virtual machine instance for one year that you can
use for gaining experience and also for trying out different software on EC2. The cur‐
rent t2.micro instance at the time of writing provides:
• Linux (Amazon, Red Hat, or SLES) or Windows