Cloud Basics – An Introduction to Cloud Computing - Grid and Cloud Computing - page 50

Table 4.2: Obstacles to adoption and growth of Cloud Computing

Obstacle Source

Availability Armbrust et al. (2009), IDC (2008a)

Security IDC (2008a)

Performance Armbrust et al. (2009), IDC (2008a)

Data lock-in Armbrust et al. (2009)

Data confidentiality and auditability Armbrust et al. (2009)

Data transfer bottlenecks Armbrust et al. (2009)

Hard to integrate with in-house IT IDC (2008a)

Lack of customizability IDC (2008a)

The user has to rely on the promise of the Cloud provider with respect to reli-
ability, performance and Quality of the Service (QoS) of the infrastructure. The
usage of Clouds is associated also with higher security and privacy risks related to
data storage and management in two ways: first because of the need to transfer data
back and forth to a Cloud so that it can be processed in a Cloud; second because data
is stored on an external infrastructure and the data owner relies on the Cloud provid-
er's assurance that no unauthorized access takes place. Furthermore, the usage of
Clouds requires an upfront investment in the integration of the own infrastructure
and applications with a Cloud. At present, there are no standards for the IaaS, PaaS,
and SaaS interfaces. This makes the choice of a Cloud provider and the investment
in integration with Clouds risky. This can result in a strong log-in effect that is
advantageous for the Cloud provider but disadvantageous for the users.
Given the risks associated with the usage of Clouds, in each case a careful evalu-
ation and comparison of the potential benefits and risks is necessary. Also, it needs to
be considered which data and processes are suitable to be used for “Cloud sourcing”
and which should better be not exposed to any organization outside the firewall.

4.5 Classification of Clouds

Clouds can generally be classified according to who the owner of the Cloud data
centres is. A Cloud environment can comprise either a single Cloud or multiple
Clouds. Thus, it can be distinguished between single-Cloud environments and
multiple-Cloud environments. The following subsections provide a classification
of single-Cloud environments according to the Cloud data centre ownership (sec.
4.5.1) and a classification of multiple-Cloud environments according to which type
of Clouds are combined (sec. 4.5.2).

4.5.1 Public Clouds vs. Private Clouds

In section 4.2, based on the review of many Cloud definitions, we have character-
ized Cloud Computing as the delivery of IT capabilities to external customers, or,
from the perspective of a user, obtaining IT capabilities from an external provider,