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Secondary storage


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  • 1. SECONDARY STORAGE by group secondary123
  • 2. random-access memory (RAM) hard-disk STORAGE An essential feature of every computer is the ability to save, or store, information
  • 3. PRIMARY STORAGE (RAM) • holds or store programs that the CPU is currently processing • provides temporary/ volatile storage • it loses its contents when power is disrupted SECONDARY STORAGE • more storage capacity • provides permanent/ nonvolatile storage • retains data and information after the computer system is turned off
  • 4. Mechanism of secondary storage WRITING : process of saving information to secondary storage devices READING : process of accessing information from secondary storage devices
  • 5. Characteristics of secondary storage • MEDIA : actual physical material that retains data & programs • CAPACITY : how much a particular storage medium can hold • STORAGE DEVICES : hardware that reads & writes to storage media • ACCESS SPEED : time required to retrieve data from a secondary storage device
  • 6. HARD DISKS • use rigid metallic platters that provide a large amount of capacity • store data & programs by altering the electromagnetic charges on platter’s surface • organize files according to : 1. tracks – concentric rings without visible grooves 2. sectors – wedge-shaped sections 3. cylinders – run through each stack of platters 4. density – how tightly electromagnetic charges can be packed next to one another
  • 7. head crash • occurs when the hard disk makes contact with the drive’s read/write heads
  • 8. TYPES OF HARD DISKS • • • • • INTERNAL located within the system unit used to store programs and data files able to store and retrieve large quantities of information quickly provide fast access fixed amount of storage • • • • • EXTERNAL removable use the same basic technology as internal disks useful to protect or secure sensitive information provide additional hard-disk capacity use for backing up contents of internal hard disk
  • 9. PERFORMANCE ENHANCEMENTS DISK CACHING - provides temporary high-speed holding area between secondary storage device & CPU RAID (redundant array of inexpensive disks) - several inexpensive hard-disk drives are connected together FILE COMPRESSION & DECOMPRESSION - files compressed before storing and decompressed before used
  • 10. Compact Disc Digital Versatile Disc Blu-ray Disc
  • 11. COMPACT DISC    Known as CD drives which were standard on many microcomputer system. CD drive can store from 650 MB to 1 GB of data on one side of a CD. Three basic type of CDs: 1.Read only=CD-ROM 2.Write once=CD-R 3.Rewritetable=CD-RW
  • 12. Read only=CR-ROM • Compact disc-read-onlymemory Write once=CD-R Rewritable=CD-RW • CD-recordable • Erasable optical disc • Can be written to once • Used to distribute large database and reference • Used to distribute large software application packages • Used to archive data and to record music downloaded from the Internet • The disc surface is not permanently altered when data is recorded • Used to create and edit multimedia presentation
  • 13. DIGITAL VERSATILE DISC Known as digital video disc  More data can be packed into the same amount of space  DVD disc can store 4.7 GB to 17 GB on a single DVD disc-17 times the capacity of CDs  Three basic type of DVDs: 1.Read only=DVD-ROM 2.Write once=DVD+R and DVD-R 3.Rewritable=DVD+RW,DVD-RW and DVD-RAM 
  • 14. Read only=DVD-ROM • Known as DVD player • Although effective for distributing music they can only contain just over an hour of fairquality video • Can provide over two hours of high-quality video and sound Write once=DVD+R and DVD-R • Known as DVD recordable • Used to create permanent archives for large amount of data and to record video • Rapidly replacing CDR drives due to their massive capacity Rewritable=DVD+R W,DVD-RW and DVD-RAM • Known as DVD random-access memory • Able to read and use any of the formats
  • 15. BLU-RAY DISC  Names comes from the blue-colored laser that is used to read the disc  Far greater capacity than DVDs  Capacity of 25 to 128 GB more than 20 times the capacity of a standard singlelayer DVD  Blu-ray disc require special drivers  Most of this drivers are capable of reading standard DVDs and CDs in addition to Blu-ray.
  • 16. Solid-State Drivers Flash Memory USB Drivers
  • 17. Solid-state Drivers (SSDs) Flash Memory USB Drives • Faster and more durable than hard disks • Require less power which can less to increased battery life for laptop and mobile devices • More expensive and generally have a lower capacity than hard disks • Widely used for tablet PCs such as iPad • Widely used in portable devices such as mobile phone and GPS navigation systems • Used in variety of specialized input devices to capture and transfer data to desktop computers • Used in digital media players like the iPod to store and play music and video files • Connect directly to a computer’s USB port to transfer files and can have capacities ranging from 1 GB to 256 GB • Have convenient size and large capacities • Transporting data and information between computers
  • 18. SECONDARY STORAGE oCloud Storage oMass Storage Devices oCareers in IT
  • 19. Cloud Storage • Internet acts as a “cloud” of servers that supply applications as a service rather than a product. • These servers provide cloud storage also known as online storage. • Eg: Google Docs-to create a word processing & spreadsheets financial management Amazon S3-storing data • Cloud servers provide storage,processing, and memory • With cloud computing software installation and upgrade are avoided 19
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  • 21. MASS STORAGE DEVICE • Mass storage refer to the tremendous amount of secondary storage required by large organization. • Mass storage devices specialized high capacity secondary storage device designed to meet ognanizational demands of data • Eg: floppy disks hard disks optical disks 21
  • 22. ENTERPRISE STORAGE SYSTEM To promote efficient and safe use of data across the networks within their organization 5 mass storage devices: File servers-dedicated computers with large storage capacities that provide users access to fast storage and retrieval of data Network attached storage (NAS)-simpler and less expensive,widely used for home and small business storage need 22
  • 23. RAID systems-larger versions of specialized devices -enhance organizational security by contantly making backup copies of files moving across the organization’s network Tape library-device automatic access to data achieved on a library tape Organizational cloud storage-high speed Internet connection to a dedicated remote organizational cloud storage server 23
  • 24. Storage Area Network (SAN) • An architecture to link remote computer storage device • Such as enterprise storage systems to computer available as locally attached drives 24
  • 25. CAREERS IN IT Software Engineering • Analyze users’ needs and create application software. Bachelor’s or advanced specialized accociate’s degree in computer science or information systems and extensive knowledge of computer and technology required. Salary range is $63 000 to $98 500. 25