Clusters | Part 2

Clusters | Part 2

Development of Clusters

The initial business oriented solution of the cluster has been ARCnet, designed by Datapoint in the year 1977, however It was not until 1984 when VAXcluster produce the operating system VAX / VMS. The ARCnet as well as VAXcluster are not just the kind of solutions which help parallel processing, but additionally help tremendously in shared file systems as well as peripheral devices.

The concept seemed to be to deliver the conveniences of parallel processing, while still be able to maintain the crucial data reliability as well as uniqueness. VAXcluster, VMScluster continues to be offered with HP OpenVMS systems operating on Itanium as well as Alpha systems.

Two additional significant features of the original commercial clusters have been the Tandem Himalaya and also the IBM S/390 Parallel Sysplex that was used solely for business purpose.

The historical past of computer clusters can be incomplete without writing about the critical role performed by the software development of the Parallel Virtual Machine (PVM). This particular open source software dependant on TCP / IP helped in the development of a virtual supercomputer – an HPC cluster – built from any of the systems that were connected through the TCP / IP.

PVM and also the utilization of Personal computer as well as inexpensive networks contributed in 1993 to a NASA venture to construct supercomputers by using clusters. These advancements additionally stimulated the independent progression to the Grid computing, in spite of the Grid style revolved about the Unix OS (operating system) and also the Arpanet.

Advantages of the Cluster Technology

Scalable parallel software programs need: great overall performance, low latency, highly accessible communications bandwidth, scalable network systems, and also a very fast access to information. A cluster satisfies all these specifications by making use of all the great resources it enjoys.

Clusters provide these functions at a fairly affordable rate:

  • High performance
  • High availability
  • High efficiency
  • Scalability

Cluster systems enable businesses to improve their own processing capability by making use of standard technologies, both computer hardware as well as computer software that could be obtained at a reasonably low cost.

Classification of Clusters

The word cluster offers diverse connotations for various groups of people today. The kinds of clusters, set up according to the use and also the services they provide, define the actual significance of the term for that group which utilizes it. The clusters may be categorized based on their features: they could possess high-performance clusters (called HPCC – High Performance Computing Clusters), clusters associated with high availability (HA – High Availability) or clusters of high efficiency (HT – High Throughput).

High performance: They are clusters where activities are performed which need high computational capability, substantial memory, or even the two simultaneously. Performing these types of work may possibly endanger the cluster resources for extended amounts of time.

High availability clusters were created in order to offer availability as well as reliability. These types of clusters making the effort to offer maximum availability involving their services. The actual reliability can be offered by software program which finds problems and permits them to recover from, although the computer hardware is actually avoided.

High Efficiency: These types of clusters whose creation was to enable running of as many functions within the least time period.

Components of a Cluster

In general, a cluster needs several software and hardware components to function. Namely:

  • Node
  • Storage
  • Operating Systems
  • Network Connections
  • Middleware
  • Communication protocols and services
  • Applications
  • Parallel Programming Environments

Nodes

Computers can be simple, multi-processor systems or workstations (workstations). In computing, a very general way, a node is a point of intersection or union of several elements that come together in the same place. However, within the word computer node can refer to different concepts depending on the area in which we move:

  • In computer networks each machine is a node, and the network is the Internet, each server is also a node.
  • In dynamic data structures a node is a record that contains a point of interest and at least one pointer to reference (point) to another node. If the structure has only a pointer, the only structure that can be built with it is a list, if the node has more than a pointer and can build more complex structures such as trees or graphs.

The cluster nodes may comprise nodes involved or not involved.

In a cluster with dedicated nodes, the nodes do not have a keyboard, mouse or monitor and its use is exclusively dedicated to performing tasks related to the cluster. While in a non-dedicated cluster with nodes, the nodes have a keyboard, mouse and monitor and its use is not solely dedicated to tasks related to the cluster, the cluster makes use of clock cycles that the user’s computer does not being used to carry out their tasks.

It is clear that when designing a cluster, nodes must have similar characteristics, i.e., they must bear some similarity of architecture and operating systems, because if it forms a fully heterogeneous cluster with nodes (there is a big difference between capacity processors, memory, hard drive) will be inefficient because the middleware delegate or assign all the node processes more computing power and distributed only when this process is saturated, so it is recommended to build a group of computers as similar as possible.

Storage

The storage may be a NAS, SAN, or internal server storage. The protocol most commonly used is NFS (Network File System), file system shared between server and nodes. However, there are specific file systems like Lustre clusters (CFS) and PVFS2.

Technologies in support of hard disk storage:

  • IDE / ATA speeds of 33, 66, 100, 133 and 166 MB / s
  • SATA speeds of 150, 300 and 600 MB / s
  • SCSI speeds of 160, 320, 640 MB / s. Provides high yields.
  • SAS: combines SATA-II and SCSI. Speeds of 300 and 600 MB / s
  • Tape drives (DLT) are used to back up for their low cost.

NAS (Network Attached Storage) is specifically dedicated to the storage device through the network (usually TCP / IP) that uses an operating system optimized to provide access via CIFS, NFS, FTP or TFTP.

For its part, DAS (Direct Attached Storage) is to connect external drives SCSI storage or a SAN (Storage Area Network) via a Fibre Channel. These connections are active.

While NAS to share storage, using the network, and has a simplified management, DAS provides improved performance and reliability by not sharing the resource.

Operating Systems

An operating system must be multi-threaded and multi-user skills. Other desirable features are ease of use and access. An operating system is a program or set of computer programs designed to ensure effective management of its resources. An operating system starts working when some one turns on the computer, and it then manages the hardware of the machine from the most basic levels, allowing the interaction with the user. Operating system can usually be found in most electronic devices that use microprocessors to operate, and that through these we can understand the machine and that it fulfills its functions (cell phones, DVD players, radios, computers, etc.). Linux, Windows, UNIX, Mac OS X are some of the very popular operating systems that have revolutionized the online world.

Continued…

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