Data storage devices


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Data storage devices

  2. 2. 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. They are read and written by a floppy disk drive (FDD). Floppy disks, initially as 8-inch (200 mm) media and later in 5.25-inch (133 mm) and 3.5- inch (89 mm) sizes, were a ubiquitous form of data storage and exchange from the mid- 1970s well into the first decade of the 21st century.[1] By 2010, computer motherboards were rarely manufactured with floppy drive support; 3 1⁄2" floppies could be used with an external USB drive, but 5 1⁄4", 8", and non-standard drives could only be handled by old equipment. While floppy disk drives still have some limited uses, especially with legacy industrial computer equipment, they have been superseded by data storage methods with much greater capacity, such as USB flash drives, portable external hard disk drives, optical discs, memory cards, and computer network.
  3. 3. DVD-RW  A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB. The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.  The primary advantage of DVD-RW over DVD-R is the ability to erase and rewrite to a DVD-RW disc. According to Pioneer, DVD-RW discs may be written to about 1,000 times before needing replacement. DVD- RW discs are commonly used to store data in a non-volatile format, such as when creating backups or collections of files. They are also increasingly used for home DVD video recorders. One benefit to using a rewritable disc is if there are writing errors when recording data, the disc is not ruined and can still store data by erasing the faulty data.  One competing rewritable format is DVD+RW. Hybrid drives that can handle both, often labeled "DVD±RW", are very popular due to the lack of a single standard for recordable DVDs.  The recording layer in DVD-RW and DVD+RW is not an organic dye, but a special phase change metal alloy, often GeSbTe. The alloy can be switched back and forth between a crystalline phase and an amorphous phase, changing the reflectivity, depending on the power of the laser beam. Data can thus be written, erased and re-written.
  4. 4. TIPE DRIVE  A tape drive is a data storage device that reads and performs digital recording, writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.  A tape drive provides sequential access storage, unlike a disk drive, which provides random access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very slow average seek times. For sequential access once the tape is positioned, however, tape drives can stream data very fast. For example, as of 2010[update] Linear Tape-Open (LTO) supported continuous data transfer rates of up to 140 MB/s, comparable to hard disk drives.
  5. 5. CD-R  Un CD-R es un formato de disco compacto grabable.(Compact Disc Recordable = Disco Compacto Grabable). Se pueden grabar en varias sesiones, sin embargo la información agregada no puede ser borrada ni sobrescrita, en su lugar se debe usar el espacio libre que dejó la sesión inmediatamente anterior.  Actualmente las grabadoras llegan a grabar CD-R a 52x, unos 7800 KB/s. Para muchos ordenadores es difícil mantener esta tasa de grabación y por ello la grabadoras tienen sistemas que permiten retomar la grabación ante un corte en la llegada de datos.  La capacidad total de un CD-R suele ser: • 650 MB = 681,57 millones de bytes • 700 MB = 734 millones de bytes. El más común. • 800 MB = 838 millones de bytes. • 900 MB = 943 millones de bytes.
  6. 6. CD-RW  A CD-RW (Compact Disc-ReWritable) is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released.  CD-RW disc require a more sensitive laser optics. Also, CD-RWs cannot be read in some CD-ROM drives built prior to 1997. CD-ROM drives will bear a "MultiRead" certification to show compatibility. CD-RW discs need to be blanked before reuse. Different blanking methods can be used, including "full" blanking in which the entire surface of the disc is cleared, and "fast" blanking in which only meta-data areas are cleared: PMA, TOC and pregap, comprising a few percent of the disc. Fast blanking is much quicker, and is usually sufficient to allow rewriting the disc. Full blanking removes traces of the former data, often for confidentiality. It may be possible to recover data from full-blanked CD-RWs with specialty data recovery equipment[citation needed]; however, this is generally not used except by government agencies due to cost.  CD-RW also have a shorter rewriting cycles life (ca. 1,000) compared to virtually all of the previously exposed types storage of media (typically well above 10,000 or even 100,000), something which however is less of a drawback considering that CD-RWs are usually written and erased in their totality, and not with repeated small scale changes, so normally wear leveling is not an issue.  Their ideal usage field is in the creation of test disks, temporary short or mid-term backups, and in general, where an intermediate solution between online and offline storage schemes is required.
  7. 7. ZIP DISK  A zip disk is a computer hardware device that stores data. A zip disk drive is somewhat like floppy disk drive, only that the size of disks inserted into the devices are different. Where a normal floppy disk can hold about 1.44 megabytes of data, a zip disk can hold around 100 megabytes of data. This means that a zip disk can hold a lot more data which is useful in today's computer market where software applications and files are becoming bigger. Files such as mp3 music files usually need to saved on 2 or more floppy disks whereas a zip disks can hold numerous mp3 files.
  8. 8. MINI DVD  Mini CDs, or “pocket CDs” are CDs with a smaller diameter and one third the capacity
  9. 9. MINI CD  Mini CDs, or “pocket CDs” are CDs with a smaller diameter and one third the capacity.
  10. 10. FLASH MEMORIES  Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM (electrically erasable programmable read-only memory) and must be erased in fairly large blocks before these can be rewritten with new data. The high density NAND type must also be programmed and read in (smaller) blocks, or pages, while the NOR type allows a single machine word (byte) to be written or read independently.
  11. 11. SECURE DIGITAL  Secure Digital (SD) is a non-volatile memory card format developed by the SD Card Association (SDA) for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models.[1]  SD comprises several families of cards:[2] the original, Standard-Capacity (SDSC) card, a High-Capacity (SDHC) card family, an eXtended-Capacity (SDXC) card family,[3] and the SDIO[4] family with input/output functions rather than just data storage.  SD also comprises three different form factors: the original size, the "mini" size, and the "micro" size (see illustration). Electrically passive adaptors allow the use of a smaller card in a host device built to hold a larger card. There are many combinations of form factors and device families.  Host devices that comply with newer versions of the specification provide backward compatibility and accept older SD cards, but older host devices do not recognize newer cards. The SDA uses several trademarked logos to enforce compliance with its specifications and assure users of compatibility.[5] This article explains several factors that can prevent the use of a newer SD card: • A newer card may offer greater capacity than the host device can handle. • A newer card may use a file system the host device cannot navigate. • Use of an SDIO card requires the host device be designed for the input/output functions the card provides. • The organization of the card was changed starting with the SDHC family. • Some vendors produced SDSC cards above 1 GB before the SDA had standardized a method of doing so.
  12. 12. TRANSFLASH O MICRO SD  microSD is a kind of removable flash memory card used for storing information. SD is an abbreviation of Secure Digital. The cards are used in cellular phones. They are also used in newer types of handheld GPS devices, portable media players, digital audio players, expandable USB flash memory drives, Nintendo DS flashcards, and digital cameras.  It is the smallest memory card that can be bought; at 15 mm × 11 mm × 1 mm (about the size of a fingernail), it is about a quarter of the size of a normal-sized SD card.[1] There are adapters that make the small microSD able to fit in things that have slots for standard SD, miniSD, Memory Stick Duo and even USB cards. But, not all of the different cards can work together. Many microSD cards sold on the internet and in stores have a standard SD adapter, so that people can use them in things that take standard SD but not microSD cards.  TransFlash and microSD cards are the same (they can be used in place of each other), but microSD has support for SDIO mode, so that non-memory cards like Bluetooth, GPS, and Near Field Communication devices to use the card also.[2]  Some people have a hard time knowing the difference between the microSD and the newer microSDHC format. The SD and SDHC act the same, but not all devices are able to be used with the newer format. This is even true with devices that have been made by SanDisk like their e200 series of MP3 players. Using 3rd party firmware, SDHC reading can sometimes be done.[3]  TransFlash cards are sold in 16MB and 32MB sizes. microSD cards are sold in many sizes, from 64 MB to 2 GB, while microSDHC cards are sold in sizes between 4 GB to 64 GB. (This is the biggest microSD card so far, and the microSDHC format can not store anything past that amount. microSD cards with even more storage will be in microSDXC format.) 
  13. 13. COMPECT FLASH  CompactFlash (CF) is a mass storage device format used in portable electronic devices. Most CompactFlash devices contain flash memory in a standardized enclosure. The format was first specified and produced by SanDisk in 1994.[4] The physical format is now used for a variety of devices.  CompactFlash became the most successful of the early memory card formats, surpassing Miniature Card, SmartMedia, and PC Card Type I in popularity. Subsequent formats, such as MMC/SD, various Memory Stick formats, and xD-Picture Card offered stiff competition. Most of these cards are smaller than CompactFlash while offering comparable capacity and speed. Proprietary memory card formats for use in professional audio and video, such as P2 and SxS, are physically larger, faster, and costlier.  CompactFlash remains popular and is even supported in some new devices. For example, in 2008, Sony chose CompactFlash as the recording medium for the HVR- MRC1K tapeless video recorder over smaller MemoryStick cards or expensive SxS cards.[5] In 2010, Canon chose CompactFlash as the recording medium for its new professional high-definition video cameras,[6] and Ikegami devices record digital video onto CompactFlash cards through an adaptor.[7]  In November 2010, Sandisk, Sony and Nikon proposed a next generation card format to the CompactFlash Association which would come in a similar form factor as CF/CFast but be based on PCI Express instead of Parallel ATA or SATA.[8] [9] The new format is targeted at high-definition camcorders and high-resolution digital photo cameras, would offer a target read and write speeds of 1 Gbps (125 Mbyte/s) and storage capabilities beyond 2 TiB, and is not backward compatible with either CompactFlash or CFast. The XQD card format has been announced by the CompactFlash Association in December 2011.[10]
  14. 14. MULTIMEDIA CARD  The MultiMediaCard (MMC) is a flash memory memory card standard. Unveiled in 1997 by SanDisk and Siemens AG, it is based on Toshiba's NAND-based flash memory, and is therefore much smaller than earlier systems based on Intel NOR-based memory such as CompactFlash. MMC is about the size of a postage stamp: 24 mm × 32 mm × 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or 8 bits at a time. It has been more or less superseded by SD (Secure Digital) card, but still sees significant use because MMCs can be used in most devices that support SD cards.  Typically, an MMC is used as a storage medium for a portable device, in a form that can easily be removed for access by a PC. For example, a digital camera would use an MMC for storing image files. With an MMC reader (typically a small box that connects via USB or some other serial connection, although some can be found integrated into the computer itself), a user could copy the pictures taken with the digital camera off to his or her computer. Modern computers, both laptops and desktops, often have SD slots, which can additionally read MMCs if the operating system drivers support them.  MMCs are available in sizes up to and including 128 GB. They are used in almost every context in which memory cards are used, like cellular phones, digital audio players, digital cameras and PDAs. Since the introduction of Secure Digital card few companies build MMC slots into their devices (an exception is some mobile devices like the Nokia 9300 communicator, where the smaller size of the MMC is a benefit), but the slightly thinner, pin-compatible MMCs can be used in almost any device that supports SD cards if the software/firmware on the device supports them.
  15. 15. SMART MEDIA  SmartMedia is a flash memory card standard owned by Toshiba, with capacities ranging from 2 MB to 128 MB. SmartMedia memory cards are no longer manufactured.
  16. 16. MINI MMC  This table provides summary of comparison of various flash memory cards, as of 2011[update].
  17. 17. XD  is a flash memory card format, used mainly in older digital cameras. xD stands for Extreme Digital.[1]  xD cards are available in capacities of 16 MiB up to 2 GiB.
  18. 18. MEMORY PEN  A USB flash drive is a data storage device that includes flash memory with an integrated Universal Serial Bus (USB) interface. USB flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. Most weigh less than 30 g.[1] As of January 2012 drives of 256GB were available, 512GB and 1 terabytes (TB) drives were in planning,[2] [3] and storage capacities as large as 2 terabytes are planned,[4] with steady improvements in size and price per capacity expected. Some allow up to 100,000 write/erase cycles (depending on the exact type of memory chip used)[5] and 10 years shelf storage time.[6][7]