Linux cluster system competition (1)

World columnist
Rawn Shah, as an expert, gives you some advice on the existing open source and closed source code cluster solutions for Linux.
Computing the number of cluster projects in Linux is the same as computing the number of startup companies in Silicon Valley. Unlike Windows NT, which has been blocked by its own closed environment, Linux has a large number of cluster systems to choose from and is suitable for different purposes and needs. However, it is not easy to determine which cluster should be used.
Part of the problem is that the term cluster is used in different scenarios. IT managers may be concerned about how to make the Server Run longer or applications run faster, while mathematicians may be more concerned about large-scale numerical computing on the server. Both require clusters, but each requires clusters with different features.
This article investigates different forms of clusters and a part of many implementations. These implementations can be purchased or obtained in the form of free software. Although not all of the solutions listed are open source code, most software follows the common practice of distributing Linux source code, especially because those who implement clusters often want to adjust system performance, to meet your needs.
Hardware
A cluster always involves hardware connections between machines. In most cases, this only refers to the "Fast Ethernet" Nic and hub. However, in the field of cutting-edge science, there are many network interface cards designed specifically for clusters. These include Myricom's Myrinet, Giganet's cLAN, and IEEE 1596 standard scalable consistent interface (SCI ). The functions of those cards not only provide high bandwidth between nodes in the cluster, but also reduce the time used to send delayed messages ). Latency is critical when status information is exchanged between nodes to keep operations synchronized.
Myricom
Myricom provides network adapters and switches. The unidirectional interconnection speed can reach up to 1.28 Gbps. Two network interfaces are available: copper and optical fiber. A copper LAN can communicate at full speed within a distance of 10 feet and operate at half speed within a distance of 60 feet. The fiber-type Myrinet can run at full speed on a 6.25-mile-long single-mode fiber or 340 feet-long multi-mode fiber. Myrinet only provides point-to-point, hub-based, or vswitch-based network configurations, but there is no limit on the number of switches that can be connected together. Adding an optical switch only increases the latency between nodes. The average latency between two directly connected nodes is 5 to 18 microseconds, much faster than Ethernet.
Cluster type
The three most common cluster types are high-performance scientific clusters, Server Load balancer clusters, and high-availability clusters.
Scientific Cluster
Generally, the first type involves developing parallel programming applications for clusters to solve complex scientific problems. This is the foundation of parallel computing, although it does not use a dedicated Parallel Supercomputer, which is composed of ten to ten thousand independent processors. However, it uses commercial systems, such as a group of single-processor or dual-processor PCs linked through high-speed connections, and communicates on the public message passing layer to run parallel applications. Therefore, you will often hear that another cheap Linux supercomputer is available. However, it is actually a computer cluster with the same processing capability as a real supercomputer. Generally, the overhead of a set of identical cluster configurations is more than $100,000. This seems too expensive for average people, but it is cheaper than dedicated supercomputer worth millions of dollars.
Server Load balancer Cluster
Server Load balancer clusters provide a more practical system for enterprises. As the name implies, the system enables the load to be evenly distributed in the computer group as much as possible. This load may be the load to be balanced by the application processing load or network traffic load. Such a system is very suitable for a large number of users running the same group of applications. Each node can handle part of the load and dynamically allocate the load between nodes to achieve a balance. This is also true for network traffic. Generally, network server applications accept too much incoming traffic and cannot be processed quickly. Therefore, you need to send the traffic to network server applications running on other nodes. Can it be optimized based on different available resources on each node or the special environment of the network?
High Availability Cluster
High Availability clusters are designed to make the overall services of the cluster as available as possible, so as to consider the error tolerance of computing hardware and software. If the master node in the HA cluster fails, it will be replaced by the secondary Node during this period of time. The secondary node is usually an image of the master node, so when it replaces the master node, it can take over its identity completely, and thus make the system environment consistent with the user.
The three basic types of a cluster are often mixed and mixed. As a result, it can be found that high-availability clusters can also balance user load between their nodes, while still trying to maintain high-availability. Similarly, you can find a parallel cluster from the group to be compiled into the application, which can perform load balancing between nodes. Although the cluster system itself is independent of the software or hardware it is using, the hardware connection plays a key role in the effective operation of the system.
Giganet
Giganet is the first supplier of Virtual Interface (VI) architecture cards for Linux. It provides cLAN cards and switches. The VI architecture is a platform-independent software and hardware system developed by Intel for cluster creation. It uses its own network communication protocol to directly exchange data between servers, rather than IP addresses, and it is not intended to become a WAN-routable system. Now, the future of VI depends on the ongoing "system I/O group" work, this team is the merger of Intel's next generation I/O team and the future I/O team led by IBM and Compaq. Currently, Giganet provides 1 Gbps unidirectional communication between nodes, with a minimum latency of 7 microseconds.
IEEE SCI
IEEE Standard SCI has a latency of less than 2.5 microseconds, and its unidirectional speed can reach 400 Mb/s (3.2 Gbps ). SCI is a ring-based network system, Unlike Ethernet. This will enable faster communication between large-scale nodes. What's more useful is the circular topology network, which has many ring structures between nodes. The two-dimensional ring surface can be represented by a grid of n multiplied by m, with a ring network in each row and each column. The three-dimensional ring surface is similar. It can be represented by a three-dimensional node mesh with a ring network on each layer. The intensive supercomputing parallel system uses a circular topology network to provide the fastest path for communication between hundreds of nodes.
Most operating systems are not restricted by operating systems or network interfaces, but by the internal PCI bus system of the server. Almost all desktop PCs usually have basic 32-bit, 33-MHz PCI, and most low-end servers only provide 133 Mb/s (1 Gbps), which limits the capabilities of those NICs. Some expensive high-end servers, such as CompaqProliant 6500 and IBM Netfinity 7000 series, all have 64-bit, 66-MHz NICs that can run at four times the speed. Unfortunately, the conflict is that more companies use low-end systems, so most vendors eventually produce and sell more low-end PCI NICs. There are also dedicated 64-bit, 66-MHz PCI NICs, but the price is much more expensive. For example, Intel provides this type of "Fast Ethernet" Nic, which costs about $400 to $500, almost five times the price of common PCI.