A. Cyberspace - also known as web space, page file space in the store pages, programs, pictures, etc.; Database space - virtual host support the database provided by the database storage space; Log space - web logs (log) file storage space. On a network server, the virtual host (also known as web space) is divided, a certain amount of disk space for the user to place the site, application components, etc., provide the necessary site data storage, transfer functions.
The emergence of the virtual host, is a major contribution to Internet technologies, the majority of Internet users in the gospel. Multiple virtual hosts to share the resources of a real host, each user to bear the cost of hardware and network maintenance costs, the cost of communication lines are significantly reduced, the Internet truly become a network that everyone can afford! Now, almost all U.S. companies (including some families) are on the network set up your own web server, in which a considerable part is used in a virtual host. So-called virtual hosting, also called "web space, a computer running the server on the Internet is divided into multiple" virtual "servers, each virtual host has a separate domain name and Internet server (to support the World Wide Web, FTP, e-mail, etc.) functions. Different virtual hosts on a single server is independent, self-management by the user. A server host can only support a certain number of virtual hosts, when more than this number, the user will feel a sharp decline in performance. Virtual mainframe technology used by the Internet server technology to save the cost of server hardware, virtual mainframe technology is mainly used in the HTTP service, one or all of the services of a server logic is divided into a number of service units and external performance for multiple server, in order to take full advantage of server hardware resources. If the classification is a system level, is called the virtual server.

Complex internal structure, internal equipment more in some high-end enterprise servers, and some also has many different equipment units or more servers in a cabinet, this server is a rackmount server. For the securities, banking, telecommunications and other enterprises, should be used with the complete failure of self-healing systems, key components should be redundant measures, use of business-critical servers can also be used dual hot-standby high-availability systems or high performance computer, the system availability can be a very good guarantee.

The so-called blade servers (accurate to say that should be called the blade server) is the standard height rack chassis can plug more than one card of the server unit, to achieve high availability and high density. Each a "blade" is actually a system motherboard. They can "on-board hard disk to start their own operating systems, such as Windows NT/2000, Linux, etc., similar to a standalone server, in this mode, each one motherboard to run their own system, service in the specified different user groups, no correlation between each other. However, administrators can use system software to the motherboard set in a server cluster. In cluster mode, the motherboard can connect up to provide high-speed network environment, and shared resources for the same user base. Insert a new blade, you can improve overall performance in the cluster. And because each "blade" is hot-swappable, so the system can easily be replaced, and maintenance time is reduced to a minimum.

  The shape of the rack-mounted servers do not appear to the computer, such as switches, there are 1U (1U = 1.75 inches = 4.45CM), 2U, 4U and other specifications. Rack-mounted servers installed in a standard 19 in. rack inside. This structure is mostly functional server. For information services companies (such as ISP / ICP / ISV / IDC), select the server must first consider the size, power consumption, heat and other physical parameters of the server because the information services companies typically use large dedicated room unified deployment and management of a large number of server resources, the room is usually equipped with tight security measures, a good cooling system, multiple backup power supply system, the engine room of the cost is quite expensive. To the cost of the service to deploy more servers directly related to the limited space usually use mechanical dimensions conform to the 19-inch industry-standard rack-mounted servers. Rack-mounted servers also have a variety of specifications, such as 1U (4.45cm high), 2U, 4U, 6U, 8U. Usually a 1U rack-mountable servers save space, but the performance and scalability is poor for some of the business is relatively fixed field of use. More than 4U high performance, scalability, and general support for more than four high-performance processor and a large number of standard hot-swappable components. Management is also very convenient, manufacturers usually provide the appropriate management and monitoring tools for critical applications for visits, but the larger the space utilization is not high.

Enterprise-class server to belong to the ranks of high-end server, the enterprise of this reason, the production of this server is not a lot, but equally there is no industry-standard hardware provides enterprise-class server needs what level, so now also see many of this do not have to develop production level of enterprise-class server companies claim to have enterprise-class server. Enterprise-class server is at least four more than the CPU symmetric processor architecture, some as high as a few dozen. Another general also has independent dual PCI channels and memory expansion board design, with high memory bandwidth, large capacity, hot-swappable hard drives and hot-swappable power, powerful data processing capability and cluster performance. This enterprise-level server chassis generally rack, and some also by several cabinet, like the mainframe. Enterprise-class server products in addition to departmental servers all server features, the biggest feature is also highly fault-tolerant, excellent scalability, fault pre-alarm function, online diagnosis and RAM, the PCI, the CPU and other hot-swap performance . Some enterprise-class server also introduces many excellent features of the mainframe computers. Such server chips are also a few major server development, the unique CPU chip manufacturers to develop their own operating system, using general UNIX (Solaris) or LINUX. Enterprise-class server for running on the need to deal with large amounts of data, high processing speed and reliability requirements of high finance, securities, transportation, post and telecommunications, communications or large enterprises. Enterprise-class server for networked computers in the hundreds of very large network, the processing speed and data security requirements. Enterprise-class server hardware configuration, system reliability is also the strongest.

The type of server is out of a mid-range servers, and generally support more symmetric dual CPU processor architecture, with complete hardware configuration, such as disk arrays, storage bays. Is most characteristic of departmental servers, in addition to all servers in the workgroup server features, also integrates extensive monitoring and management circuit, with a full range of server management capabilities, can be monitored such as temperature, voltage, fans, chassis, and other state parameters, combined with standard server management software to enable managers to keep abreast of the status of the server. The same time, most departmental servers with excellent scalability to meet the user when the volume of business increases rapidly online upgrade system to fully protect the user's investment. It is dispersed in the enterprise network the basic data acquisition unit with the highest level of data center to maintain the smooth connectivity necessary link, usually the first choice for medium-sized enterprises can also be used in finance, telecommunications and other industries. Departmental servers generally use IBM, SUN and HP respective CPU chip, these chips are generally RISC architecture, the operating system is generally the UNIX family of operating systems, has been widely applied in the LINUX also departmental servers. Departmental servers can be connected to computer users around the 100, apply to the higher processing speed and system reliability, small and medium-sized enterprise networks, the hardware configuration is relatively high, and its reliability is higher than the work group server, of course, its The prices are higher (typically the sum of about five high-performance PC price). Such servers require installation of more parts, so the chassis is usually large, using the rack.

Workgroup server is an entry-level server level, but still belong to the class of low-end server. Can also be seen from the name, it can only be connected to a working group (50 units) then the multi-user, network size is smaller, the stability of the server is also not as high as we talk about enterprise-class server application environment, of course, other performance requirements corresponding to lower. The main features of the work group server with the following aspects: one usually only supports single or dual CPU architecture application server (but not absolute, especially the SUN workgroup server it is able to support up to four processors working group server, of course, the price of this type of server a somewhat different) 2 ECC memory support for large capacity and enhanced server management features of the SM bus more comprehensive, manageable, and easy to maintain with Intel server CPU and for Windows / NetWare network operating system, but also part of the data processing of the UNIX family of operating systems to meet the small and medium-sized network users, file sharing, Internet access and a simple database application needs. Workgroup server than the entry-level server performance improved function has been enhanced, there is a certain degree of scalability, fault tolerance and redundancy performance is still not perfect, we can not meet the application of large-scale database systems, but the price than the former a lot more expensive, generally equivalent to 2 to 3 high-performance PC brand of the total price.

The type of server is the most basic server, and most low-end server. With the increasing of PC technology, many entry-level servers and PC configuration or similar, so some people think that the entry-level servers and PC server equivalent. Such server contains the server features are not typically have the following characteristics: 1 some basic hardware redundancy, such as hard drives, power supplies, fans, etc., but not required; usually SCSI interface hard disk, and now ; Part 3 parts SATA serial interface also supports hot-swappable, such as hard drives and memory, these are not necessary; 4 is usually only one CPU, but not absolute; five largest memory capacity to support 16GB. These servers using the Windows or NetWare network operating system, can fully meet the office-based small and medium-sized network users of file sharing, data processing, Internet access and a simple database application needs. This server and is very similar to the PC, in general, there are many small companies simply use a high-performance brand of PC as a server, this server in terms of performance or price, with a high-performance PC brand of almost the same. Terminal even entry-level servers is relatively limited (usually around 20), Moreover, in terms of stability, scalability, and fault-tolerant redundancy, poor performance, only applies to large databases for data exchange, the daily work of network traffic, without Long-term non-stop small business to boot. But I want to clarify that some relatively large-scale server development, enterprise-class server manufacturers in the back, we wish to be divided into several grades, including most low-end of an enterprise-class server grade is called "entry-level enterprise-class server, "said the entry-level is not and we said above, the entry-level" have the same meaning, but this division is still relatively small. Another point is, this server is generally used for Intel's server CPU chips based on Intel architecture (commonly known as "IA structure"), of course, this is not a rigid standard requirements, but because of the server application level needs and the limit of the price.

x86 server: also known as CISC (complex instruction set) architecture server, usually a PC server, a PC-based architecture, Intel or other compatible x86 instruction set processor chip and the Windows operating system server. Cheap, good compatibility, poor stability, insecurity, mainly used in small and medium-sized enterprises and non-critical business.

Non-x86 server: mainframes, minicomputers and UNIX servers, they use RISC (reduced instruction set) or EPIC (Parallel Instruction Code) processor, UNIX and other proprietary operating systems servers, RISC processor IBM's POWER and PowerPC processors, cooperative research and development of the SUN and Fujitsu SPARC processor, EPIC processor is Intel developed Itanium processor. This server is expensive, closed system, but good stability, performance, mainly used in the core system in the financial, telecommunications and other large enterprises.