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Data Storage - GovITwiki


Data Storage

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As a whole, the term data storage (also called Computer data storage, storage or memory) refers to those computer devices, components and media which are capable of recording, retaininG AND enabling access to the digital data used for computing.

Contents

Storage at The Client or PC Level

  • Primary storage, also known as computer memory, is chiefly designed to be directly accessible to a system's central processing unit CPU. The CPU continuously reads instructions stored there and executes them as required.
    • ROM - Read Only Memory
    • RAM - Random Access Memory
  • Secondary Storage
    • PC- or Workstation-based
    • Network- or system-connected storage devices (see below)

Network or system-connected Storage Devices

A secondary or tertiary storage may connect to a computer. The most common of these attached devices are listed below.

  • Direct-attached storage (DAS) is a traditional mass storage, that does not use any network. This is still a most popular approach. This term was coined lately, together with NAS and SAN.
  • Network-attached storage (NAS) is mass storage attached to a computer which another computer can access at file level over a local area network, a private wide area network WAN, or in the case of online file storage, over the Internet. NAS is commonly associated with the Network File System (NFS} protocol and CIFS/SMB protocols.
  • Storage area network (SAN) is a specialized network, that provides other computers with storage capacity. The crucial difference between NAS and SAN is the former presents and manages file systems to client computers, whilst a latter provides access at block-addressing (raw) level, leaving it to attaching systems to manage data or file systems within the provided capacity. SAN is commonly associated with Fibre Channel networks.

Other Details on Storage

This list contains mostly glossary definitions. Pages are slowly being expanded by the govITwiki community.

Removable media devices

  • DVD (digital versatile disc) - a popular type of removable media that is the same dimensions as a CD but stores up to 6 times as much information. It is the most common way of transferring digital video.
    • DVD-ROM Drive - a device used for reading data from a DVD.
    • DVD Writer - a device used for both reading and writing data to and from a DVD.
    • DVD-RAM Blu-ray - a high-density optical disc format for the storage of digital information, including high-definition video. 
  • HD DVD - a high-density optical disc format and successor to the standard DVD. It was a discontinued competitor to the Blu-ray format.
  • Floppy disk Zip drive - an outdated medium-capacity removable disk storage system, first introduced by Iomega in 1994.
  • USB flash drive - a flash memory data storage device integrated with a USB interface, typically small, lightweight, removable, and rewritable


Links

Lessons from the U.S. Dept. of Transportation - Management and Operations - System Data and Storage

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