Mass storage
Encyclopedia
In computing
, mass storage refers to the storage of large amounts of data
in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries
, RAID
systems, hard disk drives, magnetic tape
drives, optical disc
drives, magneto-optical disc drives, drum memory
(historic), floppy disk
drives (historic), punched tape
(historic) and holographic memory (experimental). Mass storage includes devices with removable
and non-removable media. It does not include random access memory (RAM), which is volatile
in that it loses its contents after power loss.
The notion of "large" amounts of data is of course highly dependent on the time frame and the market segment, as mass storage device capacity has increased by many orders of magnitude since the beginnings of computer technology in the late 1940s and continues to grow; however, in any time frame, common mass storage devices have tended to be much larger and at the same time much slower than common realizations of the contemporaneous primary storage technology. The term mass storage was used in the PC marketplace for devices far smaller than devices that were not considered mass storage in the mainframe marketplace.
Mass storage devices are characterized by:
Today, magnetic disks are the predominant storage media in personal computer
s. Optical discs, however, are almost exclusively used in the large-scale distribution of retail software, music and movies because of the cost and manufacturing efficiency of the molding process used to produce DVD
and compact disc
s and the nearly-universal presence of reader drives
in personal computers and consumer appliances. Flash memory
(in particular, NAND flash) has an established and growing niche as a replacement for magnetic hard disk
s in high performance enterprise computing installations because it has no moving parts (making it more robust) and has a much lower latency
; as removable storage such as USB sticks, because in lower capacity ranges it can be made smaller and cheaper than hard disks; and on portable devices such as notebook computers and cell phones because of its lower size and weight, better tolerance of physical stress caused by e.g. shaking or dropping, and low power consumption.
The design of computer architecture
s and operating system
s are often dictated by the mass storage and bus
technology of their time. Desktop operating systems such as Windows
are now so closely tied to the performance characteristics of magnetic disks that it is difficult to deploy them on other media like flash memory without running into space constraints, suffering serious performance problems or breaking applications.
. The choice of file system is often important in maximizing the performance of the device: general purpose file systems (such as NTFS
and HFS
, for example) tend to do poorly on slow-seeking optical storage such as compact discs.
Some relational database
s can also be deployed on mass storage devices without an intermediate file system or storage manager. Oracle
and MySQL
, for example, can store table data directly on raw block devices.
On removable media
, archive formats (such as tar archives on magnetic tape
, which pack file data end-to-end) are sometimes used instead of file systems because they are more portable
and simpler to stream
.
On embedded computers, it is common to memory map
the contents of a mass storage device (usually ROM or flash memory) so that its contents can be traversed as in-memory data structures or executed directly by programs.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, mass storage refers to the storage of large amounts of data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries
Tape library
In computer storage, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device which contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes...
, RAID
RAID
RAID is a storage technology that combines multiple disk drive components into a logical unit...
systems, hard disk drives, magnetic tape
Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
drives, optical disc
Optical disc
In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...
drives, magneto-optical disc drives, drum memory
Drum memory
Drum memory is a magnetic data storage device and was an early form of computer memory widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria....
(historic), floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
drives (historic), punched tape
Punched tape
Punched tape or paper tape is an obsolete form of data storage, consisting of a long strip of paper in which holes are punched to store data...
(historic) and holographic memory (experimental). Mass storage includes devices with removable
Removable media
In computer storage, removable media refers to storage media which is designed to be removed from the computer without powering the computer off.Some types of removable media are designed to be read by removable readers and drives...
and non-removable media. It does not include random access memory (RAM), which is volatile
Volatile memory
Volatile memory, also known as volatile storage, is computer memory that requires power to maintain the stored information, unlike non-volatile memory which does not require a maintained power supply...
in that it loses its contents after power loss.
The notion of "large" amounts of data is of course highly dependent on the time frame and the market segment, as mass storage device capacity has increased by many orders of magnitude since the beginnings of computer technology in the late 1940s and continues to grow; however, in any time frame, common mass storage devices have tended to be much larger and at the same time much slower than common realizations of the contemporaneous primary storage technology. The term mass storage was used in the PC marketplace for devices far smaller than devices that were not considered mass storage in the mainframe marketplace.
Mass storage devices are characterized by:
- Sustainable transfer speed
- Seek time
- Cost
- Capacity
Today, magnetic disks are the predominant storage media in personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
s. Optical discs, however, are almost exclusively used in the large-scale distribution of retail software, music and movies because of the cost and manufacturing efficiency of the molding process used to produce DVD
DVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
and compact disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
s and the nearly-universal presence of reader drives
CD-ROM
A CD-ROM is a pre-pressed compact disc that contains data accessible to, but not writable by, a computer for data storage and music playback. The 1985 “Yellow Book” standard developed by Sony and Philips adapted the format to hold any form of binary data....
in personal computers and consumer appliances. Flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
(in particular, NAND flash) has an established and growing niche as a replacement for magnetic hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
s in high performance enterprise computing installations because it has no moving parts (making it more robust) and has a much lower latency
Latency
Latency or latent may refer to:*Latency period , the time between exposure to a pathogen, chemical or radiation, and when symptoms first become apparent...
; as removable storage such as USB sticks, because in lower capacity ranges it can be made smaller and cheaper than hard disks; and on portable devices such as notebook computers and cell phones because of its lower size and weight, better tolerance of physical stress caused by e.g. shaking or dropping, and low power consumption.
The design of computer architecture
Computer architecture
In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....
s and operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s are often dictated by the mass storage and bus
Computer bus
In computer architecture, a bus is a subsystem that transfers data between components inside a computer, or between computers.Early computer buses were literally parallel electrical wires with multiple connections, but the term is now used for any physical arrangement that provides the same...
technology of their time. Desktop operating systems such as Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
are now so closely tied to the performance characteristics of magnetic disks that it is difficult to deploy them on other media like flash memory without running into space constraints, suffering serious performance problems or breaking applications.
Usage
Mass storage devices used in desktop and most server computers typically have their data organized in a file systemFile system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
. The choice of file system is often important in maximizing the performance of the device: general purpose file systems (such as NTFS
NTFS
NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....
and HFS
HFS
HFS may stand for:* Hyperfine structure* Hereditarily finite set* Hexafluorosilicic acid* WHFS , 'HFS was a slang abbreviation for the radio stations with that call sign in the Washington / Baltimore area...
, for example) tend to do poorly on slow-seeking optical storage such as compact discs.
Some relational database
Relational database
A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...
s can also be deployed on mass storage devices without an intermediate file system or storage manager. Oracle
Oracle database
The Oracle Database is an object-relational database management system produced and marketed by Oracle Corporation....
and MySQL
MySQL
MySQL officially, but also commonly "My Sequel") is a relational database management system that runs as a server providing multi-user access to a number of databases. It is named after developer Michael Widenius' daughter, My...
, for example, can store table data directly on raw block devices.
On removable media
Removable media
In computer storage, removable media refers to storage media which is designed to be removed from the computer without powering the computer off.Some types of removable media are designed to be read by removable readers and drives...
, archive formats (such as tar archives on magnetic tape
Magnetic tape data storage
Magnetic tape data storage uses digital recording on to magnetic tape to store digital information. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs actual writing or reading of data is a tape drive...
, which pack file data end-to-end) are sometimes used instead of file systems because they are more portable
Porting
In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...
and simpler to stream
Streaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...
.
On embedded computers, it is common to memory map
Memory map
In computer science, a memory map is a structure of data that indicates how memory is laid out. Memory maps can have a different meaning in different parts of the operating system....
the contents of a mass storage device (usually ROM or flash memory) so that its contents can be traversed as in-memory data structures or executed directly by programs.
See also
- Data storageData storage devicethumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....
for general overview of storage methods- Computer data storage for storage methods specific to computing field
- Disk storageDisk storageDisk storage or disc storage is a general category of storage mechanisms, in which data are digitally recorded by various electronic, magnetic, optical, or mechanical methods on a surface layer deposited of one or more planar, round and rotating disks...
for both magnetic and optical recording of disks - Magnetic tape data storageMagnetic tape data storageMagnetic tape data storage uses digital recording on to magnetic tape to store digital information. Modern magnetic tape is most commonly packaged in cartridges and cassettes. The device that performs actual writing or reading of data is a tape drive...
- Computer storage densityComputer storage densityMemory storage density is a measure of the quantity of information bits that can be stored on a given length of track, area of surface, or in a given volume of a computer storage medium. Generally, higher density is more desirable, for it allows greater volumes of data to be stored in the same...
- List of device bandwidths
- Solid-state driveSolid-state driveA solid-state drive , sometimes called a solid-state disk or electronic disk, is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block i/o hard disk drive...
- RAM diskRAM diskA RAM disk or RAM drive is a block of RAM that a computer's software is treating as if the memory were a disk drive...
- RAIDRAIDRAID is a storage technology that combines multiple disk drive components into a logical unit...
- Disk storage
- Computer data storage for storage methods specific to computing field