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Cloud Server
A virtual private server (VPS) or virtual dedicated server (VDS) is a virtual machine sold as a service by an Internet hosting company. A virtual private server runs its own copy of an operating system (OS), and customers may have superuser-level access to that operating system instance, so they can install almost any software that runs on that OS. For many purposes, it is functionally equivalent to a dedicated physical server and, being software-defined, can be created and configured more easily. A virtual server costs less than an equivalent physical server. However, as virtual servers share the underlying physical hardware with other VPS, performance may be lower depending on the workload of any other executing virtual machines. Virtualization The force driving server virtualization is similar to that which led to the development of time-sharing and multiprogramming in the past. Although the resources are still shared, as under the time-sharing model, virtualization provi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Machine
In computing, a virtual machine (VM) is the virtualization or emulator, emulation of a computer system. Virtual machines are based on computer architectures and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two. Virtual machines differ and are organized by their function, shown here: * ''System virtual machines'' (also called full virtualization VMs, or SysVMs) provide a substitute for a real machine. They provide the functionality needed to execute entire operating systems. A hypervisor uses native code, native execution to share and manage hardware, allowing for multiple environments that are isolated from one another yet exist on the same physical machine. Modern hypervisors use hardware-assisted virtualization, with virtualization-specific hardware features on the host CPUs providing assistance to hypervisors. * ''Process virtual machines'' are designed to execute computer programs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtualization
In computing, virtualization (abbreviated v12n) is a series of technologies that allows dividing of physical computing resources into a series of virtual machines, operating systems, processes or containers. Virtualization began in the 1960s with IBM CP/CMS. The control program CP provided each user with a simulated stand-alone System/360 computer. In hardware virtualization, the '' host machine'' is the machine that is used by the virtualization and the ''guest machine'' is the virtual machine. The words ''host'' and ''guest'' are used to distinguish the software that runs on the physical machine from the software that runs on the virtual machine. The software or firmware that creates a virtual machine on the host hardware is called a '' hypervisor'' or ''virtual machine monitor''. Hardware virtualization is not the same as hardware emulation. Hardware-assisted virtualization facilitates building a virtual machine monitor and allows guest OSes to be run in isolation. Deskt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Private Cloud
A virtual private cloud (VPC) is an on-demand configurable pool of shared resources allocated within a '' public cloud'' environment, providing a certain level of isolation between the different organizations (denoted as ''users'' hereafter) using the resources. The isolation between one VPC user and all other users of the same cloud (other VPC users as well as other public cloud users) is achieved normally through allocation of a private IP subnet and a virtual communication construct (such as a VLAN or a set of encrypted communication channels) per user. In a VPC, the previously described mechanism, providing isolation within the cloud, is accompanied with a virtual private network (VPN) function (again, allocated per VPC user) that secures, by means of authentication and encryption, the remote access of the organization to its VPC resources. With the introduction of the described isolation levels, an organization using this service is in effect working on a 'virtually private' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloud Computing
Cloud computing is "a paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with self-service provisioning and administration on-demand," according to International Organization for Standardization, ISO. Essential characteristics In 2011, the National Institute of Standards and Technology (NIST) identified five "essential characteristics" for cloud systems. Below are the exact definitions according to NIST: * On-demand self-service: "A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider." * Broad network access: "Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets, laptops, and workstations)." * Pooling (resource management), Resource pooling: " The provider' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of Platform Virtualization Software
Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors. General Features * Providing any virtual environment usually requires some overhead of some type or another. Native usually means that the virtualization technique does not do any CPU level virtualization (like Bochs), which executes code more slowly than when it is directly executed by a CPU. Some other products such as VMware and Virtual PC use similar approaches to Bochs and QEMU, however they use a number of advanced techniques to shortcut most of the calls directly to the CPU (similar to the process that JIT compiler uses) to bring the speed to near native in most cases. However, some products such as coLinux, Xen, z/VM (in real mode) do not suffer the cost of CPU-level s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multitenancy
Software multitenancy is a software architecture in which a single instance of software runs on a server and serves multiple tenants. Systems designed in such manner are "shared" (rather than "dedicated" or "isolated"). A tenant is a group of users who share a common access with specific privileges to the software instance. With a multitenant architecture, a software application is designed to provide every tenant a dedicated share of the instance—including its data, configuration, user management, tenant individual functionality and non-functional properties. Multitenancy contrasts with multi-instance architectures, where separate software instances operate on behalf of different tenants. Some commentators regard multitenancy as an important feature of cloud computing. Adoption History of multitenant applications Multitenant applications have evolved from—and combine some characteristics of—three types of services: # Timesharing: From the 1960s companies rented spac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Hosting
A web hosting service is a type of Internet hosting service that hosts websites for clients, i.e. it offers the facilities required for them to create and maintain a site and makes it accessible on the World Wide Web. Companies providing web hosting services are sometimes called ''web hosts''. Typically, web hosting requires the following: * one or more server (computing), servers to act as the Host (network), host(s) for the sites; servers may be physical or hardware virtualization, virtual; * colocation centre, colocation for the server(s), providing physical space, electricity, and Internet connectivity; * Domain Name System configuration to define name(s) for the sites and point them to the hosting server(s); * a web server running on the host; * for each site hosted on the server: ** space on the server(s) to hold the files making up the site; ** site-specific configuration; ** often, a database; ** software and credentials allowing the client to access these, enabling them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dedicated Server
A dedicated hosting service, dedicated server, or managed hosting service is a type of Internet hosting in which the client leases an entire server not shared with anyone else. This is more flexible than shared hosting, as organizations have full control over the server(s), including choice of operating system, hardware, etc. There is also another level of dedicated or managed hosting commonly referred to as complex managed hosting. Complex managed hosting applies to both physical dedicated servers, hybrid server and virtual servers, with many companies choosing a hybrid (combination of physical and virtual) hosting solution. There are many similarities between standard and complex managed hosting but the key difference is the level of administrative and engineering support that the customer pays for – owing to both the increased size and complexity of the infrastructure deployment. The provider steps in to take over most of the management, including security, memory, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenVZ
OpenVZ (Open Virtuozzo) is an operating-system-level virtualization technology for Linux. It allows a physical server to run multiple isolated operating system instances, called containers, virtual private servers (VPSs), or virtual environments (VEs). OpenVZ is similar to Solaris Containers and LXC. OpenVZ compared to other virtualization technologies While virtualization technologies such as VMware, Xen and Kernel-based Virtual Machine, KVM provide full virtualization and can run multiple operating systems and different kernel versions, OpenVZ uses a single Linux kernel and therefore can run only Linux. All OpenVZ containers share the same architecture and kernel version. This can be a disadvantage in situations where guests require different kernel versions than that of the host. However, as it does not have the overhead of a true hypervisor, it is very fast and efficient. Memory allocation with OpenVZ is soft in that memory not used in one virtual environment can be used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Containerization (computing)
In software engineering, containerization is operating-system-level virtualization or application-level virtualization over multiple network resources so that software applications can run in isolated user spaces called ''containers'' in any cloud or non-cloud environment, regardless of type or vendor. The term "container" is overloaded, and it is important to ensure that the intended definition aligns with the audience's understanding. Usage Each ''container'' is basically a fully functional and portable cloud or non-cloud computing environment surrounding the application and keeping it independent of other environments running in parallel. Individually, each container simulates a different software application and runs isolated processes by bundling related configuration files, libraries and dependencies. But, collectively, multiple containers share a common operating system kernel (OS). In recent times, containerization technology has been widely adopted by cloud computing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel-based Virtual Machine
Kernel-based Virtual Machine (KVM) is a free and open-source virtualization module in the Linux kernel that allows the Kernel (operating system), kernel to function as a hypervisor. It was merged into the Mainline Linux, mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules. KVM was originally designed for x86 processors but has since been porting, ported to IBM ESA/390, ESA/390, PowerPC, IA-64, and ARM architecture, ARM. The IA-64 port was removed in 2014. KVM supports hardware-assisted virtualization for a wide variety of guest operating systems including BSD, Solaris (operating system), Solaris, Microsoft Windows, Windows, Haiku (operating system), Haiku, ReactOS, Plan 9 from Bell Labs, Plan 9, AROS Research Operating System, AROS, macOS, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Random Access Memory
Random-access memory (RAM; ) is a form of electronic computer memory that can be read and changed in any order, typically used to store working data and machine code. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the physical location of data inside the memory, in contrast with other direct-access data storage media (such as hard disks and magnetic tape), where the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as media rotation speeds and arm movement. In today's technology, random-access memory takes the form of integrated circuit (IC) chips with MOS (metal–oxide–semiconductor) memory cells. RAM is normally associated with volatile types of memory where stored information is lost if power is removed. The two main types of volatile random-access semiconductor memory are static ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
