Computer Storage Drive

• Computer Storage Definition
• Types Of Computer Storage Drives
• Computer Storage Drives Information
• Computer Storage Devices

Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism. Notable types are the hard disk drive (HDD) containing a non-removable disk, the floppy disk drive (FDD) and its removable floppy disk, and various optical disc drives (ODD) and associated optical disc media.

Backup your Mac with a portable or desktop hard drive. Safekeep all of your music, photographs, movies and more. Buy online with fast, free shipping. Dec 30, 2020 How an external drive connects to your PC or Mac is second only to the type of storage mechanism it uses in determining how fast you'll be able to access data. These connection types are ever in.

(The spelling disk and disc are used interchangeably except where trademarks preclude one usage, e.g. the Compact Disc logo. The choice of a particular form is frequently historical, as in IBM's usage of the disk form beginning in 1956 with the 'IBM 350 disk storage unit').

Background[edit]

Audio information was originally recorded by analog methods (see Sound recording and reproduction). Buy microsoft word 2016. Similarly the first video disc used an analog recording method. In the music industry, analog recording has been mostly replaced by digital optical technology where the data is recorded in a digital format with optical information.

The first commercial digital disk storage device was the IBM 350 which shipped in 1956 as a part of the IBM 305 RAMAC computing system. The random-access, low-density storage of disks was developed to complement the already used sequential-access, high-density storage provided by tape drives using magnetic tape. Vigorous innovation in disk storage technology, coupled with less vigorous innovation in tape storage, has reduced the difference in acquisition cost per terabyte between disk storage and tape storage; however, the total cost of ownership of data on disk including power and management remains larger than that of tape.^[1]

Disk storage is now used in both computer storage and consumer electronic storage, e.g., audio CDs and video discs (VCD, standard DVD and Blu-ray).

Data on modern disks is stored in fixed length blocks, usually called sectors and varying in length from a few hundred to many thousands of bytes. Gross disk drive capacity is simply the number of disk surfaces times the number of blocks/surface times the number of bytes/block. In certain legacy IBM CKD drives the data was stored on magnetic disks with variable length blocks, called records; record length could vary on and between disks. Capacity decreased as record length decreased due to the necessary gaps between blocks. Portable usb drive.

Access methods[edit]

Digital disk drives are block storage devices. Each disk is divided into logical blocks (collection of sectors). Blocks are addressed using their logical block addresses (LBA). Read from or writing to disk happens at the granularity of blocks.

Originally the disk capacity was quite low and has been improved in one of several ways. Improvements in mechanical design and manufacture allowed smaller and more precise heads, meaning that more tracks could be stored on each of the disks. Advancements in data compression methods permitted more information to be stored in each of the individual sectors.

The drive stores data onto cylinders, heads, and sectors. The sectors unit is the smallest size of data to be stored in a hard disk drive and each file will have many sectors units assigned to it. The smallest entity in a CD is called a frame, which consists of 33 bytes and contains six complete 16-bit stereo samples (two bytes × two channels × six samples = 24 bytes). The other nine bytes consist of eight CIRC error-correction bytes and one subcode byte used for control and display.

The information is sent from the computer processor to the BIOS into a chip controlling the data transfer. This is then sent out to the hard drive via a multi-wire connector. Once the data is received onto the circuit board of the drive, they are translated and compressed into a format that the individual drive can use to store onto the disk itself. The data is then passed to a chip on the circuit board that controls the access to the drive. The drive is divided into sectors of data stored onto one of the sides of one of the internal disks. An HDD with two disks internally will typically store data on all four surfaces.

The hardware on the drive tells the actuator arm where it is to go for the relevant track and the compressed information is then sent down to the head which changes the physical properties, optically or magnetically for example, of each byte on the drive, thus storing the information. A file is not stored in a linear manner, rather, it is held in the best way for quickest retrieval.

Rotation speed and track layout[edit]

Computer Storage Definition

Mechanically there are two different motions occurring inside the drive. One is the rotation of the disks inside the device. The other is the side-to-side motion of the head across the disk as it moves between tracks.

There are two types of disk rotation methods:

• constant linear velocity (used mainly in optical storage) varies the rotational speed of the optical disc depending upon the position of the head, and
• constant angular velocity (used in HDDs, standard FDDs, a few optical disc systems, and vinyl audio records) spins the media at one constant speed regardless of where the head is positioned.

Track positioning also follows two different methods across disk storage devices. Storage devices focused on holding computer data, e.g., HDDs, FDDs, Iomega zip drives, use concentric tracks to store data. During a sequential read or write operation, after the drive accesses all the sectors in a track it repositions the head(s) to the next track. This will cause a momentary delay in the flow of data between the device and the computer. In contrast, optical audio and video discs use a single spiral track that starts at the inner most point on the disc and flows continuously to the outer edge. When reading or writing data there is no need to stop the flow of data to switch tracks. This is similar to vinyl records except vinyl records started at the outer edge and spiraled in toward the center.

Interfaces[edit]

The disk drive interface is the mechanism/protocol of communication between the rest of the system and the disk drive itself. Storage devices intended for desktop and mobile computers typically use ATA (PATA) and SATA interfaces. Enterprise systems and high-end storage devices will typically use SCSI, SAS, and FC interfaces in addition to some use of SATA.

Types Of Computer Storage Drives

Basic terminology[edit]

• Disk - Generally refers to magnetic media and devices.
• Disc - Required by trademarks for certain optical media and devices.
• Platter – An individual recording disk. A hard disk drive contains a set of platters. Developments in optical technology have led to multiple recording layers on DVDs.
• Spindle – the spinning axle on which the platters are mounted.
• Rotation – Platters rotate; two techniques are common:
  • Constant angular velocity (CAV) keeps the disk spinning at a fixed rate, measured in revolutions per minute (RPM). This means the heads cover more distance per unit of time on the outer tracks than on the inner tracks. This method is typical with computer hard drives.
  • Constant linear velocity (CLV) keeps the distance covered by the heads per unit time fixed. Thus the disk has to slow down as the arm moves to the outer tracks. This method is typical for CD drives.
• Track – The circle of recorded data on a single recording surface of a platter.
• Sector – A segment of a track
• Low level formatting – Establishing the tracks and sectors.
• Head – The device that reads and writes the information—magnetic or optical—on the disk surface.
• Arm – The mechanical assembly that supports the head as it moves in and out.
• Seek time – Time needed to move the head to a new position (specific track).
• Rotational latency – Average time, once the arm is on the right track, before a head is over a desired sector.
• Data transfer rate - The rate at which user data bits are transferred from or to the medium. Technically, this would more accurately be entitled the 'gross' data transfer rate.

See also[edit]

References[edit]

1. ^Richard L. Moore; et al. (May 3, 2007). 'Disk and Tape Storage Cost Models'(PDF). San Diego Supercomputer Center, UCSD. Retrieved 20 February 2013.

In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. In general the term is uses as large in relation to contemporaneous disk drives, but it has been used large in relation to RAM as for example with floppy disks.

Devices and/or systems that have been described as mass storage include tape libraries, RAID systems, and a variety of computer drives such as hard disk drives, magnetic tape drives, magneto-optical disc drives, optical disc drives, memory cards, and solid-state drives. It also includes experimental forms like holographic memory. Mass storage includes devices with removable and non-removable media.^[1][2] It does not include random access memory (RAM).

There are two broad classes of mass storage: local data in devices such as smartphones or computers, and enterprise servers and data centers for the cloud. Connect windows pc to android phone. For local storage, SSDs are on the way to replacing HDDs. Considering the mobile segment from phones to notebooks, the majority of systems today is based on NAND Flash. As for Enterprise and data centers, storage tiers have established using a mix of SSD and HDD. ^[3]

Definition[edit]

The notion of 'large' amounts of data is of course highly dependent on the time frame and the market segment, as 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 contemporaneous primary storage technology.

Papers^[4][5][6] at the 1966 Fall Joint Computer Conference^[7] (FJCC) used the term mass storage for devices substantially larger than contemporaneous hard disk drives. Similarly, a 1972 analysis identified mass storage systems from Ampex (Terabit Memory) using video tape, Precision Industries (Unicon 690-212) using lasers and International Video (IVC-1000) using video tape^[8] and states 'In the literature, the most common definition of mass storage capacity is a trillion bits.'.^[9] The first IEEE conference on mass storage was held in 1974^[10] and at that time identified mass storage as 'capacity on the order of 10¹² bits' (1 gigabyte).^[11] In the mid-1970s IBM used the term to in the name of the IBM 3850 Mass Storage System, which provided virtual disks backed up by Helical scan magnetic tape cartridges, slower than disk drives but with a capacity larger than was affordable with disks.^[12] The term mass storage was used in the PC marketplace for devices, such as floppy disk drives, far smaller than devices that were not^[a] considered mass storage in the mainframe marketplace.

Mass storage devices are characterized by:

• Sustainable transfer speed
• Cost
• Capacity

Storage media[edit]

Magnetic disks are the predominant storage media in personal computers. 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 discs and the nearly-universal presence of reader drives in personal computers and consumer appliances.^[13]Flash memory (in particular, NAND flash) has an established and growing niche as a replacement for magnetic hard disks in high performance enterprise computing installations due to its robustness stemming from its lack of moving parts, and its inherently much lower latency when compared to conventional magnetic hard drive solutions. Flash memory has also long been popular as removable storage such as USB sticks, where it de facto makes up the market. This is because it scales better cost-wise in lower capacity ranges, as well as its durability. It has also made its way onto laptops in the form of SSDs, sharing similar reasons with enterprise computing: Namely, markedly high degrees of resistance to physical impact, which is again, due to the lack of moving parts, as well as a performance increase over conventional magnetic hard disks and markedly reduced weight and power consumption. Flash has also made its way onto cell phones.^[14][15]

The design of computer architectures and operating systems are often dictated by the mass storage and bus technology of their time.^[16]

Usage[edit]

Mass storage devices used in desktop and most server computers typically have their data organized in a file system. 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 databases 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.

See also[edit]

• Data storage for general overview of storage methods
  • Computer data storage for storage methods specific to computing field
    • Disk storage for both magnetic and optical recording of disks

Notes[edit]

1. ^E.g., the obsolete 1956 IBM 350 stored 5 million six-bit characters, larger than contemporary 1.44 and 2.88 MB floppies.

Computer Storage Drives Information

References[edit]

1. ^'Definition of: mass storage'. PC Magazine. Ziff Davis. Archived from the original on 2016-07-05. Retrieved 2019-10-10.
2. ^Sterling, Thomas; Anderson, Matthew; Brodowicz, Maciej (2018). '17 – Mass storage'. High performance computing. Morgan Kaufmann (Elsevier). ISBN978-0-12-420158-3.
3. ^https://www.hyperstone.com/en/NAND-Flash-is-displacing-hard-disk-drives-1249,12728.html, NAND Flash is displacing Hard Disk Drives, Retrieved 29. May 2018
4. ^1966FJCC, pp. 711-742, TECHNOLOGIES AND SYSTEMS FOR ULTRA-HIGH CAPACITY STORAGE. sfn error: no target: CITEREF1966FJCC (help)
5. ^1966FJCC, pp. 711-716, UNICON Computer Mass Memory System, C.H.BECKER. sfn error: no target: CITEREF1966FJCC (help)
6. ^1966FJCC, pp. 735-742, A Photo-Digital Mass Storage System, J. D. KUEHLER, H. R. KERBY. sfn error: no target: CITEREF1966FJCC (help)
7. ^1966 Fall Joint Computer Conference. AFIPS Conference Proceedings. Vol. 29. Spartan Books. ISBN978-1-4503-7893-2. 1966FJCC.
8. ^Norman F. Schneidewind; Gordon H. Syms; Thomas L. Grainger; Robert J. Carden (July 1972). A SURVEY AND ANALYSIS OF HIGH DENSITY MASS STORAGE DEVICES AND SYSTEMS (Report). US Navy Postgraduate School, Monterey CA. CiteSeerX10.1.1.859.1517. NPS-55SS72071A. Retrieved December 3, 2020.
9. ^NPS-55SS72071A, p. 6, A. Definition and Uses of Mass Storage.
10. ^The 35^th conference was held in 2019.
11. ^Bacon, G. C. (October 1974). 'Mass Storage Workshop Report'. Computer. IEEE. 7 (10): 64–65. doi:10.1109/MC.1974.6323336. S2CID29301138. Retrieved December 3, 2020.
12. ^Introduction to the IBM 3850 Mass Storage System (MSS)(PDF) (Second ed.). IBM. November 1974. GA32-0028-1.
13. ^Taylor, Jim. 'DVD FAQ'. Archived from the original on 2009-08-22. Retrieved 2007-07-08. In 2003, six years after introduction, there were over 250 million DVD playback devices worldwide, counting DVD players, DVD PCs, and DVD game consoles.
14. ^Gonsalves, Antone (23 May 2007). 'Micron predicts flash memory will replace disk drives'. EETimes..
15. ^Heingartner, Douglas (2005-02-17). 'Flash Drives: Always on the Go, Without Moving Parts'. New York Times. Retrieved 2008-02-24..
16. ^Patterson, Dave (June 2003). 'A Conversation With Jim Gray'. ACM Queue. 1 (4). Archived from the original(– ^{Scholar search}) on April 21, 2005.. (A discussion of recent trends in mass storage.)

Computer Storage Devices