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A logical disk, logical volume or virtual disk (VD [1] or vdisk [2] for short) 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 ...
In computer data storage, a volume or logical drive is a single accessible storage area with a single file system, typically (though not necessarily) resident on a single partition of a hard disk. Although a volume might be different from a physical disk drive, it can still be accessed with an operating system's logical interface.
A full file reference (pathname in today's parlance) consists of a filename, a filetype, and a disk letter called a filemode (e.g. A or B). Minidisks can correspond to physical disk drives, but more typically refer to logical drives, which are mapped automatically onto shared devices by the operating system as sets of virtual cylinders.
IBM in its 1983 release of PC DOS version 2.0 was an early if not first use of the term partition to describe dividing a block storage device such as an HDD into physical segments. The term's usage is now ubiquitous. [citation needed] Other terms used include logical disk, [4] minidisk, [5] portions, [6] pseudo-disk, [6] section, [6] slice [7 ...
Further, a RAID array may be a single SCSI device, but may contain many logical units, each of which is a "virtual" disk—a stripe set or mirror set constructed from portions of real disk drives. The SCSI ID, WWN, etc. in this case identifies the whole subsystem, and a second number, the logical unit number (LUN) identifies a disk device (real ...
Later, optical disc drives and flash memory units are also classified as DASD. [2] [3] The term DASD contrasts with sequential access storage device such as a magnetic tape drive, and unit record equipment such as a punched card device. A record on a DASD can be accessed without having to read through intervening records from the current ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 13 November 2024. Portable Document Format, a digital file format For other uses, see PDF (disambiguation). Portable Document Format Adobe PDF icon Filename extension.pdf Internet media type application/pdf, application/x-pdf application/x-bzpdf application/x-gzpdf Type code PDF (including a single ...
This preserves an old version of the LV, the snapshot, which may be later reconstructed by overlaying the copy-on-write table atop the current LV. Unless the volume management supports both thin provisioning and discard, once an LE in the origin volume is written to, it is permanently stored in the snapshot volume.