Transcript
SECONDARY STORAGEby group secondary123
STORAGEAn essential feature of every computer is the ability to save, or store, information
random-access memory (RAM) hard-disk
• holds or store programs that the CPU is currently processing
• provides temporary/ volatile storage
• it loses its contents when power is disrupted
• more storage capacity• provides permanent/
nonvolatile storage• retains data and
information after the computer system is turned off
PRIMARY STORAGE (RAM)
SECONDARY STORAGE
Mechanism of secondary storage
WRITING : process of saving information to secondary storage devices
READING : process of accessing information from secondary storage devices
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
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 grooves2. sectors – wedge-shaped sections3. cylinders – run through each
stack of platters4. density – how tightly
electromagnetic charges can be packed next to one another
head crash
• occurs when the hard disk makes contact with the drive’s read/write heads
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
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
OPTICAL DISCS
Compact Disc
Digital Versatile
Disc
Blu-ray Disc
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
Read only=CR-ROM
• Compact disc-read-only-memory
• Used to distribute large database and reference
• Used to distribute large software application packages
Write once=CD-R
• CD-recordable
• Can be written to once
• Used to archive data and to record music downloaded from the Internet
Rewritable=CD-RW
• Erasable optical disc
• The disc surface is not permanently altered when data is recorded
• Used to create and edit multimedia presentation
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
Read only=DVD-ROM
• Known as DVD player
• Although it effective for distributing music they can only contain just over an hour of fair-quality 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 CD-R drives due to their massive capacity
Rewritable=DVD+RW,DVD-RW and DVD-RAM
• Known as DVD random-access memory
• Able to read and use any of the formats
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 single-layer DVD
Blu-ray disc require special drivers
Most of this drivers are capable of reading standard DVDs and CDs in addition to Blu-ray.
SOLID-STATE STORAGE
Flash Memory
USB Drivers
Solid-State Drivers
Solid-state Drivers (SSDs)
• 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
Flash Memory• 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
USB Drives
• 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
SECONDARY STORAGE
oCloud StorageoMass Storage Devices
oCareers in IT
• 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 & spreadsheetsMint.com-for financial managementAmazon S3-storing data
• Cloud servers provide storage,processing, and memory• With cloud computing software installation and upgrade are avoided
19
Cloud Storage
20
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 diskshard disksoptical disks
22
ENTERPRISE STORAGE SYSTEM
To promote efficient and safe use of data across the networks within their organization5 mass storage devices:
File servers-dedicated computers with large storage capacities that provide users access to fast storage and retrieval of dataNetwork attached storage (NAS)-simpler and less expensive,widely used for home and small business storage need
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 tapeOrganizational cloud storage-high speed Internet connection to a dedicated remote organizational cloud storage server
23
• An architecture to link remote computer storage device • Such as enterprise storage systems to computer available
as locally attached drives
24
Storage Area Network (SAN)
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
CAREERS IN IT
top related