A cluster is a type of parallel or distributed computer system, which consists of a collection of inter-connected stand-alone computers working together as a single integrated computing resource.

1. Raja’ Masa’deh

2.  How to Run Applications Faster ?
 What is a Cluster.
 Motivation for Using Clusters.
 Key Benefits of Clusters.
 Major issues in cluster design.
 Cluster Architecture.
 Cluster components.
 Types of Cluster.
 Cluster Classification.
 Advantages & Disadvantages of Cluster computing.

3.  There are three ways to improve performance:
◦ Work harder
◦ Work smarter
◦ Get help
 To speed up computation in Computer system :
◦ Use faster hardware: e.g. reduce the time per instruction.
◦ Optimized algorithms and techniques
◦ Doing parallel processing by multiple processors or multiple
computers cooperated to solve problem

4.  A cluster is a type of parallel or distributed computer system,
which consists of a collection of inter-connected stand-alone
computers working together as a single integrated computing
resource.
 Cluster platforms was driven by a number of academic
projects, such as Beowulf ,Berkeley NOW (Network Of
Workstations) , and HPVM (High Performance Virtual Machine)
that prove the advantage of clusters over other traditional
platforms

5. Beowulf cluster NOW-1 cluster

6.  Many science and engineering problems today require
large amounts of computational resources and cannot be
executed in a single machine.
 High cost of high performance computers.
 Large numbers of under-utilized machines with a wasted
computational power.
 Communications bandwidth between computers is
increasing.

7.  High performance: The reason for the growth in use of clusters is
that they have significantly reduced the cost of processing power.
 Scalability: a cluster uses the combined processing power of
compute nodes to run cluster-enabled applications.
 System availability : offer inherent high system availability due to
the redundancy of hardware, operating systems, and applications

8.  Scalable Performance: This refers to the fact that scaling of the
resources (cluster nodes, memory capacity, I/O bandwidth,
etc.) leads to proportional increase in performance. Of course,
both scale up and scale down are needed, depending on the
application demand or cost-effectiveness considerations.
 Availability Support: Clusters can provide cost-effective high
availability with lots of redundancy in processors, memories,
disks, I/O devices, networks, operating system images, etc.

9.  Cluster Job Management: Clusters try to achieve high system
utilization, out of traditional workstations or PC nodes that are
normally not highly utilized. Job management software is
needed to provide batching, load balancing, parallel
processing, and other functionality.
 Fault Tolerance and Recovery: Cluster of machines can be
designed to eliminate all single points of failure. Through
redundancy, the cluster can tolerate faulty condition up to
certain extent

11.  The key components of a cluster include:
 Multiple standalone computers (PCs, Workstations, or
SMPs).
 Operating systems.
 High-performance interconnections.
 Middleware.
 Parallel programming environments.
 Applications.

12.  Clusters, built using commercial-off-the-shelf (COTS)
hardware components.
 Such as :Personal Computers (PCs), workstations, and
Symmetric Multiple-Processors (SMPs).
 These technologies are solution for cost-effective parallel
computing for their availability and low cost.

13.  A cluster operating system is desired to have the following features:
1. Manageability: Ability to manage and administrate local and remote
resources.
2. Stability: Support for robustness against system failures with system
recovery.
3. Performance: All types of operations should be optimized and efficient.
4. Extensibility: Provide easy integration of cluster-specific extensions.

14. 5. Scalability: Able to scale without impact on performance.
6. Support: User and system administrator support is essential.
7. Heterogeneity: Portability over multiple architectures to support a
cluster consisting of heterogeneous hardware components.
 Popular OS used on nodes of clusters:
 Linux
 Microsoft NT
 SUN Solaris

15.  Clusters need to incorporate fast interconnection
technologies in order to support high-bandwidth and low-
latency inter-processor communication between cluster
nodes. Examples of NW technologies:
 Fast Ethernet (100Mbps)
 Gigabit Ethernet (1Gbps)
 SCI (Dolphin - MPI- 12 usec latency)
 ATM - Myrinet (1.2Gbps)

16.  Resides between OS and applications and offers an
infrastructure for supporting:
◦ Single System Image (SSI)
◦ System Availability (SA)
 SSI makes collection of computers appear as a single
machine (globalized view of system resources)
 SA supports check pointing and process migration.

17.  Threads (PCs, SMPs, NOW, ..)
◦ POSIX Threads
◦ Java Threads
 MPI
◦ Linux, NT, on many Supercomputers
 PVM
 Software DSMs

18.  Sequential
 Parallel/distributed (cluster-aware applications)
Grand challenging applications
Weather Forecasting
Quantum Chemistry
Molecular Biology Modeling
Engineering Analysis (CAD/CAM)
Web servers, data-mining

19. 1. High availability clusters (HA) .
2. Network Load balancing clusters.
3. High performance Clusters.

20.  High-availability clusters (also known as Failover Clusters)
are implemented for the purpose of improving the
availability of services which the cluster provides.
 Provide redundant nodes that can act as backup systems in
the event of failure.
 Support mission critical applications.

22.  Load balancing is a computer networking methodology to
distribute workload across multiple computers.
 Load balancing clusters operate by routing all the workload over
one or more load balancing front end nodes, which then
distribute the workload efficiently between remaining active
back end nodes.
 Web servers, all available servers process requests.

24.  HPC clusters used to solve high & advanced computation
problems.
 They are designed to take advantage of parallel processing
power of multiple nodes.
 They are commonly used to perform function that require
nodes to communicate as they perform their tasks- when
calculation results from one node will affect future results
from another.

26. Cluster ClassificationAttributes
SlackCompactPackaging
DecentralizedCentralizedControl
HeterogeneousHomogeneousHomogeneity
ExposedEnclosedSecurity

27.  The cluster nodes can be compactly or slackly packaged.
 In a compact cluster, the nodes are closely packaged in one or
more racks sitting in a room, and the nodes are not attached
to peripherals (monitors, keyboards, mice, etc.).
 In a slack cluster, the nodes are attached to their usual
peripherals (i.e. they are complete SMPs, workstations, and
PCs), and they may be located in different rooms, different
buildings, even wide-area in remote regions.

28.  Centralized cluster: all the nodes are owned, controlled,
managed by a central administrator.
 Decentralized cluster, the nodes have individual owners, so
this makes the system administration of such a cluster very
difficult. It also requires special techniques for process
scheduling, workload migration, check pointing, etc.

29.  A homogeneous cluster means that the nodes adopt the same
platform (same processor architecture and the same OS).
 A heterogeneous cluster uses nodes of different platforms.
 In a homogeneous cluster, a process can migrate to another
node and continue execution.
 This is not feasible in a heterogeneous cluster, because
different platform, as the binary code will not be executable

30.  Intracluster communication can be either exposed or
enclosed.
 In an exposed cluster, the communication paths among the
nodes are exposed to the outside world.
 An outside machine can access the communication paths,
and thus individual nodes.

31.  Such exposed clusters are easy to implement, but have
several disadvantages:
• Exposed intracluster communication is not secure, unless
the communication subsystem performs additional work
to ensure the privacy and security.
• Outside communications may disrupt intracluster
communications in an unpredictable manner .

32.  In an Enclosed cluster, intracluster communication is
shielded from the outside world ( more secure ).
 A disadvantage is that there is currently no standard for
efficient, enclosed intracluster communication.

34.  Manageability: with cluster, large numbers of components are
combined to work as a single entity. So, management becomes
easy.
 Single System Image: also this illusion makes the user not
worried about the cluster components, he only needs to manage
a single system image.
 High Availability: if one component fails, then some other
component can takes its place, and user can continue to work
with the system.

35.  Programmability Issues: when the components are different in
terms of software from each other, and then there may be issues
when combining all of them together as a single entity.
 Problem in Finding Fault: it is difficult to find fault and
determine which component has a problem.
 Difficult to handle by a non specialist : cluster computing
involves merging different or same components together, so a
non- professional person may find it difficult to manage.

36.  We have discussed the motivation for cluster computing as
well as the technologies available for building cluster
systems using commodity-based hardware and software
components to achieve high performance, availability, and
scalability .
 The cluster computing is a more cost effective platform
compared to traditional high performance platforms.

37.  Kiranjot Kaur1, Anjandeep Kaur Rai, A Comparative Analysis: Grid, Cluster
and Cloud Computing, International Journal of Advanced Research in
Computer and Communication Engineering Vol. 3, Issue 3, March 2014.
 Kai Hwang, Geoffrey Fox, and Jack Dongarra , Distributed Computing:
Cluster, Grids and Clouds, May 2, 2010.
 Domenico Laforenza et al., Grid and Cluster Computing: Models,
Middleware and Architectures, Springer- Verlag Berlin Heidelberg 2006.
 R. Buyya , High Performance Cluster Computing: Architectures and
Systems, vol. 1, Prentice Hall, 1999.