Exercise 5
Task 1
❖ Types of distributed systems
➢ There are 3 types of Distributed Systems: distributed computing systems, distributed
information systems, and pervasive systems
➢ High performance distributed computing
▪ In cluster computing the underlying hardware consists of a collection of similar
workstations or PCs, closely connected by means of a high-speed local-area network. In
addition, each node runs the same operating system.
▪ The situation becomes very different in the case of grid computing. This subgroup
consists of distributed systems that are often constructed as a federation of computer
systems, where each system may fall under a different administrative domain and may
be very different when it comes to hardware, software, and deployed network
technology.
▪ From the perspective of grid computing, a next logical step is to simply outsource the
entire infrastructure that is needed for compute-intensive applications. In essence, this
is what cloud computing is all about
➢ Cluster computing
▪ It became financially and technically attractive to build a supercomputer using off-the-
shelf technology by simply hooking up a collection of relatively simple computers in a
high-speed network (Diagram 1.7)
▪ However, several modern cluster computers have been moving away from these
symmetric architectures to more hybrid solutions in which the middleware is
functionally partitioned across different nodes
➢ Grid computing
▪ In Grid Computing no assumptions are made concerning similarity of hardware,
operating systems, networks, administrative domains, security policies, etc.
▪ The architecture consists of four layers. The lowest fabric layer provides interfaces to
local resources at a specific site. The connectivity layer consists of communication
protocols for supporting grid transactions that span the usage of multiple resources and
it also performs authentication.
▪ The resource layer is responsible for managing a single resource. The resource layer is
thus seen to be responsible for access control, and hence will rely on the authentication
performed as part of the connectivity layer.
▪ Collective layer deals with handling access to multiple resources and typically consists of
services for resource discovery, allocation and scheduling of tasks onto multiple
resources, data replication, and so on.
▪ Application layer consists of the applications that operate within a virtual organization,
and which make use of the grid computing environment. (Diagram 1.8)
▪ Typically, the collective, connectivity, and resource layer form the heart of what could be
called a grid middleware layer.
➢ Cloud computing
▪ Concept of utility computing by which a customer could upload tasks to a data centre
and be charged on a per-resource basis.
▪ Utility computing formed the basis for what is now called cloud computing.
▪ In practice, clouds are organized into four layers,
▪ Hardware: The lowest layer is formed by the means to manage the necessary hardware:
processors, routers, but also power and cooling systems.
