Evaluation Criteria to Run Scientific Applications in the Cloud - Cloud Computing with e-Science Applications - page 10

• Application porting procedures : This consists of the adaptation
that needs to be performed in the application for it to be executed
in the cloud. The evaluation covers changes in both the source code
and the execution environment.
To evaluate the performance of the cloud, it is necessary to compare it with
a traditional system, which is a system whose performance the user knows
and will be used as the basis for comparison. For a fair comparison, both the
base and cloud systems need to present similar characteristics, mainly the
number of cores of each system. The purpose is to have a direct comparison
between a known system, the base system, and a new system, the cloud.
1.6 Analysis of Cloud Providers
1.6.1 Amazon Web Services
Amazon web services are one of the most widely known cloud providers.
Many different kinds of services are offered, including storage, platform, and
hosting services. Two of the most-used services of Amazon are the Amazon
Elastic Compute Cloud (EC2) and Amazon Simple Storage Service (S3).
Amazon EC2 is an IaaS model and may be considered the central part of
Amazon's cloud platform. It was designed to make web scaling easier for
users. The interaction with the user is done through a web interface that
permits obtaining and configuring any desired computing capacity with
little difficulty. Amazon EC2 does not use regular configurations for the cen-
tral processing unit (CPU) of instances available. Instead, it uses an abstrac-
tion called elastic compute units (ECUs). According to Amazon, each ECU
provides the equivalent CPU capacity of a 1.0- to 1.2-GHz 2007 Opteron or
2007 Xeon processor. Amazon S3 is also an IaaS model and consists of a stor-
age solution for the Internet. It provides storage through web service inter-
faces, such as REST and SOAP. There is no particular defined format of the
stored objects; they are simple files. Inside the provider, the stored objects
are organized into buckets, which are an Amazon proprietary method. The
names of these buckets are chosen by the user, and they are accessible using
a hypertext transfer protocol (HTTP) uniform resource locator (URL), with
a regular web browser. This means that Amazon S3 can be easily used to
replace static web hosting infrastructure. One example of an Amazon S3
user is the Dropbox service, provided as SaaS for the final user, with the user
having a certain amount of storage in the cloud to store any desired file.
1.6.2 Rackspace
Rackspace was founded in 1998 as a typical hosting company with several
levels of user support. The company developed the cloud services offered