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
Mint.com-for financial management
Amazon S3-storing data
• Cloud servers provide storage,processing, and memory
• With cloud computing software installation and upgrade are avoided
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20. 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 disks
hard disks
optical disks
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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
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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
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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
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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.
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