Chapter 8 Types of Storage

September 19,2016.Monday

Storage

•Storage holds data, instructions, and information for future use 

•A storage medium is the physical material on

 which is a computer keeps data, instructions, and

 information.

•Capacity is the number of bytes a storage medium

 can hold

•A storage device is the computer hardware that

 records and/or retrieves items to and from

 storage media

•Access time measures:

        –The amount of time it takes a storage device

          to locate an item on a storage medium

        –The time required to deliver an item from memory to the processor

Hard Disks              

•A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information

•Hard disks can store data using longitudinal

 recording or perpendicular recording

•Characteristics of a hard disk include:

-capacity 

-Platters 

-Read/write 

-Cylinders 

-Sectors and Tracks 

-Revolutions per Minute 

-Transfer Rate

-Access Time

•Formatting is the process of dividing the disk into

 tracks and sectors so that the operating system

 can store and locate data and information on the

 disk

How a hard Disk works 

•The hard disk arms move the read/write head, which reads items and writes items in the drive

–Location often is referred to by its cylinder

Types

•A head crash occurs when a read/write head touches the surface of a platter

•Always keep a backup of your hard disk

How Disk Cache works 

•RAID (redundant array of independent disks) is a group of two or more integrated hard disks

•A network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage

•External hard disk is a separate free-standing hard disk that connects to your computer with a cable or wirelessly

•Removable hard disk is a hard disk that you insert and remove from a drive

•Internal and external hard disks are available in miniature sizes

•A disk controller consists of a special-purpose chip and electronic circuits that control the transfer of data, instructions, and information from a disk to and from the system bus and other components of the computer

   -SATA

   -EIDE

   -SCSI

   -SAS

Flash Memory Storage

•Flash memory chips are a type of solid state
 media and contain no moving parts

•Solid state drives (SSDs) have several advantages
 over magnetic hard disks:

  -Faster access time 

  -Faster transfer rates 

  -Generate less heat and consume less power

  -Last longer

•A memory card is a removable flash memorydevice that you insert and remove from a slot in a computer, mobile device, or card reader/writer

  -CompactFlash (CF)

  -Secure Digital (SD)

  -Secure Digital High Capacity (SDHC)

  -microSD

  -microSDHC

  -xD Picture card 

  -Memory stick 

  -Memory Stick Micro (M2)

•USB flash drives plug into a USB port on a computer or mobile device

•An ExpressCard module is a removable device that fits in an ExpressCard slot

•Developed by the PCMCIA

•Commonly used in notebook computers

•An ExpressCard module is a removable device that fits in an ExpressCard slot

•Developed by the PCMCIA

•Commonly used in notebook computers

Cloud Storage

•Cloud storage is an Internet service that provides

 storage to computer users

•Users subscribe to cloud storage for a variety of reasons:

  -Access files from any computer 

  -Store large files instantaneously 

  -Allow others to access their files  

  -View  time-critical data and images immediately 

  -Store offsite backups

  -Provide data center functions

Optical Discs

•An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser

•Typically store software, data, digital photos, movies, and music

•Read only vs. rewritable

How a laser Reads Data on an Optical Disc

•Optical discs commonly store items in a single track that spirals from the center of the disc to the edge

•Track is divided into evenly sized sectors

•Care of optical discs

Archive disc

•Stores photos from an online photo center 

•Resolution usually is 7200 pixels per photo 

•Cost is determined by the number of photos being

 stored 

Picture CD

•Single-session CD-ROM that stores digital

 versions of film

•Typically uses a 1024 x 1536 resolution 

•Many photo centers offer Picture CD services

Other Types of Storage

-Tape 

-Magnetic stripe cards and smart cards 

-Microfilm and microfiche 

-Enterprise storage

•Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information

•A tape drive reads and writes data and information on a tape

•A magnetic stripe card contains a magnetic stripe that stores information

•A smart card stores data on a thin microprocessor embedded in the card

•Microfilm and microfiche store microscopic images

 of documents on a roll or sheet film

•Enterprise storage stores huge volumes of data

 and information for large businesses

–Uses special hardware for heavy use, maximum availability, and maximum efficiency

Putting It All Together