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Virtual disk and virtual drive are software components that emulate an actual disk storage device.
Virtual disks and virtual drives are common components of virtual machines in hardware virtualization, but they are also widely used for various purposes unrelated to virtualization, such as for the creation of logical disks.
A virtual drive is a software component that emulates an actual disk drive, such as an optical disc drive, a floppy disk drive, or a hard disk drive. To other programs, a virtual drive looks and behaves like an actual physical device.
A virtual disk may be in any of the following forms:
In hardware virtualization, virtual machines implement virtual drives as part of their efforts to emulate the behavior of an actual machine. As with an ordinary computer, a virtual machine needs one virtual drive and one disk image to start up, except when it is performing a network boot. More virtual drives are added as needed.
Virtual optical drives are used on physical computers to transfer the contents of the optical disks onto hard disk drives. Doing so helps in resolving the problem of the short life span of CDs and DVDs and takes advantage of the faster data transfer rate of hard disk drives. However, virtual optical drives are also used for software piracy: early computer games used disc existence verification to ensure licensed use, which can be circumvented using virtual optical drives. As a countermeasure, the StarForce copy protection scheme attempts to thwart disc virtualization. Modern video games have migrated to online product activation as part of their distribution process.
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Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.
In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used.
The term server highlights the role of the machine in the traditional client–server scheme, where the clients are the workstations using the storage. A file server does not normally perform computational tasks or run programs on behalf of its client workstations.
A direct-access storage device (DASD) is a secondary storage device in which "each physical record has a discrete location and a unique address". IBM coined the term DASD as a shorthand describing hard disk drives, magnetic drums, and data cells. Later, optical disc drives and flash memory units are also classified as DASD. The term DASD contrasts with sequential storage media such as magnetic tape, and unit record equipment such as card devices like card readers and punches.
A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is usually made by creating a sector-by-sector copy of the source medium, thereby perfectly replicating the structure and contents of a storage device independent of the file system. Depending on the disk image format, a disk image may span one or more computer files.
A live CD is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A Live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.
An optical disc image is a disk image that contains everything that would be written to an optical disc, disk sector by disc sector, including the optical disc file system. ISO images are expected to contain the binary image of an optical media file system, including the data in its files in binary format, copied exactly as they were stored on the disc. The data inside the ISO image will be structured according to the file system that was used on the optical disc from which it was created.
A USB flash drive is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable and much smaller than an optical disc. Most weigh less than 30 g (1 oz). Since first appearing on the market in late 2000, as with virtually all other computer memory devices, storage capacities have risen while prices have dropped. As of March 2016, flash drives with anywhere from 8 to 256 gigabytes (GB) were frequently sold, while 512 GB and 1 terabyte (TB) units were less frequent. As of 2018, 2 TB flash drives were the largest available in terms of storage capacity. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and are thought to last between 10 and 100 years under normal circumstances.
Network-attached storage (NAS) is a file-level computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. NAS is specialized for serving files either by its hardware, software, or configuration. It is often manufactured as a computer appliance – a purpose-built specialized computer. NAS systems are networked appliances that contain one or more storage drives, often arranged into logical, redundant storage containers or RAID. Network-attached storage removes the responsibility of file serving from other servers on the network. They typically provide access to files using network file sharing protocols such as NFS, SMB, or AFP. From the mid-1990s, NAS devices began gaining popularity as a convenient method of sharing files among multiple computers. Potential benefits of dedicated network-attached storage, compared to general-purpose servers also serving files, include faster data access, easier administration, and simple configuration.
A diskless node is a workstation or personal computer without disk drives, which employs network booting to load its operating system from a server.
A No-disc crack, No-CD crack or No-DVD crack is an executable file or a special "byte patcher" program which allows a user to circumvent certain Compact Disc and DVD copy protection schemes. They allow the user to run computer software without having to insert their required CD-ROM or DVD-ROM. This act is a form of software cracking. No-CD cracks specific to a variety of games and other software distributed on CD-ROM or DVD-ROM can be found on the Internet from various reverse engineering websites or file sharing networks. No-CD cracks have legal uses, such as creating backups of legally owned software or avoiding the inconvenience of placing a CD or DVD-ROM in the drive every time the software is being used, although they can also be used to circumvent laws in many countries by allowing the execution of full versions of non-legally owned applications or time-limited trials of the applications without the original disc.
Parallels Workstation is the first commercial software product released by Parallels, Inc., a developer of desktop and server virtualization software. The Workstation software consists of a virtual machine suite for Intel x86-compatible computers which allows the simultaneous creation and execution of multiple x86 virtual computers. The product is distributed as a download package. Parallels Workstation has been discontinued for Windows and Linux as of 2013.
In computing, data recovery is a process of salvaging (retrieving) inaccessible, lost, corrupted, damaged or formatted data from secondary storage, removable media or files, when the data stored in them cannot be accessed in a usual way. The data is most often salvaged from storage media such as internal or external hard disk drives (HDDs), solid-state drives (SSDs), USB flash drives, magnetic tapes, CDs, DVDs, RAID subsystems, and other electronic devices. Recovery may be required due to physical damage to the storage devices or logical damage to the file system that prevents it from being mounted by the host operating system (OS).
In computer science, a data buffer is a region of a physical memory storage used to temporarily store data while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device or just before it is sent to an output device. However, a buffer may be used when moving data between processes within a computer. This is comparable to buffers in telecommunication. Buffers can be implemented in a fixed memory location in hardware—or by using a virtual data buffer in software, pointing at a location in the physical memory. In all cases, the data stored in a data buffer are stored on a physical storage medium. A majority of buffers are implemented in software, which typically use the faster RAM to store temporary data, due to the much faster access time compared with hard disk drives. Buffers are typically used when there is a difference between the rate at which data is received and the rate at which it can be processed, or in the case that these rates are variable, for example in a printer spooler or in online video streaming. In the distributed computing environment, data buffer is often implemented in the form of burst buffer that provides distributed buffering service.
In computer science, storage virtualization is "the process of presenting a logical view of the physical storage resources to" a host computer system, "treating all storage media in the enterprise as a single pool of storage."
A logical disk, logical volume or virtual disk is a virtual device that provides an area of usable storage capacity on one or more physical disk drive(s) in a computer system. The disk is described as logical or virtual because it does not actually exist as a single physical entity in its own right. The goal of the logical disk is to provide computer software with what seems a contiguous storage area, sparing them the burden of dealing with the intricacies of storing files on multiple physical units. Most modern operating systems provide some form of logical volume management.
In computing, virtualization or virtualisation is the act of creating a virtual version of something, including virtual computer hardware platforms, storage devices, and computer network resources.
In computer science, memory virtualization decouples volatile random access memory (RAM) resources from individual systems in the data centre, and then aggregates those resources into a virtualized memory pool available to any computer in the cluster. The memory pool is accessed by the operating system or applications running on top of the operating system. The distributed memory pool can then be utilized as a high-speed cache, a messaging layer, or a large, shared memory resource for a CPU or a GPU application.
This glossary of computer hardware terms is a list of definitions of terms and concepts related to computer hardware, i.e. the physical and structural components of computers, architectural issues, and peripheral devices.
A floppy disk hardware emulator is a device that emulates a floppy disk drive with a solid state or network storage device that is plug compatible with the drive it replaces, similar to how solid-state drives replace mechanical hard disk drives.