Transcript Chapter 7 Storage - University of Mary

CIS 101: Introduction to Computers
Chapter
7
Storage
Levi Krein
Associate Professor CIS
What is storage?

Holds data, instructions, and information for future use
 Storage medium is physical material used for storage
 Also called secondary storage
Levi Krein
p. 7.02 Fig. 7-1
Associate Professor CIS
What is capacity?

Number of bytes (characters) a storage medium can hold
Kilobyte (KB)
1 thousand
Megabyte (MB) 1 million
Gigabyte (GB)
Terabyte (TB)
Petabyte (PB)
1 billion
1 trillion
1 quadrillion
Exabyte (EB)
1 quintillion
Zettabyte (ZB)
1 sextillion
Yottabyte (YB)
1 septillion
Largest single database is
500 Terabytes at an east
coast university (nuclear
accelerator data)
Levi Krein
Associate Professor CIS
How does volatility compare?
 Storage medium is nonvolatile—contents retained when
power is off
 Memory is volatile—holds data and instructions temporarily
Levi Krein
Associate Professor CIS
What is a storage device?
Hardware = I/O or Read/Write Devices
Reading
Memory
Writing
Process of transferring
items from storage
media to memory
SDRAM
Process of transferring
items from memory
to storage media
Functions as source
of Input
Records Output
Levi Krein
Associate Professor CIS
Access time is the combination of two tasks:

Time it takes storage device to locate item on storage medium

Time required to deliver item from memory to processor
Remember, the access time of RAM is
200,000 times faster than a hard drive
faster
transfer
rates
Data Transfer Rate
Stores …
Primary Storage
Memory (most RAM)
Items waiting to be interpreted
and executed by the processor
Secondary Storage
Hard Disk
slower
transfer
rates
Flash Memory Cards
and USB Flash Drives
CDs and DVDs
Tape
Operating system, application
software, user data and information
Digital pictures or files
to be transported
Krein
Software, backups,Levi
movies,
music
Backups
Associate Professor CIS
Link to “How Hard Disks Work”
What is a hard disk?




hard disk installed
in system unit
High-capacity storage
Consists of several
inflexible, circular
platters that store items
magnetically
Components enclosed in
airtight, sealed case for
protection
High-speed platters spin
at 5400-7200 rpm
Levi
Hard Drive
= Krein
7200 rpm
120 rpSecond
Associate
Professor CIS
Magnetic Disks
Track
is narrow
recording band
that forms full
circle on disk
Formatting prepares disk for use
Sector
stores up to
512 bytes
of data
How does disk storage work?
Disks are Magnetic = data is stored by
aligning positive & negative particles

Levi Krein
Associate Professor CIS
Magnetic Disks
What are characteristics of a hard disk?
Sample Hard Disk Characteristics
Advertised capacity
Platters
Read/write heads
Cylinders
Bytes per second
Sectors per track
Sectors per drive
Revolutions per minute
Transfer rate
Access time
750 GB
p. 361 Fig. 7-11
Fall 2006
120 GB
3
6
16,383
512
63
234,441,648
7,200
133 MB per second
8.9 ms
actual
disk
capacity
Check the
capacity of our
lab computers
Associate Professor
CIS
Levi Krein
How does a hard drive look?
Platters are made of metal
(aluminum), glass, or ceramic &
has a metal surface that can be
magnetized.
Levi Krein
Associate Professor CIS
Video: Install a New Hard Drive
Speed up your computer with a new hard drive
Hard Drive
Video
Levi Krein
Associate Professor CIS
What is a cylinder?
platter



track
sector
Vertical section of
track through all
platters
Same track number
on multiple
surfaces
Single movement of
read/write head
arms accesses all
platters in cylinder;
reduce access time
read/write
head
platter
sides
Levi Krein
cylinder
Associate Professor CIS
Maintaining Hard Disk Data
A little Preventive maintenance!
Defragment = reorganize
files to make better used of
space; programs will run
faster
Two ways: 1 – Start, Accessories, System Tools
2 – My Computer, Properties,
Disk Cleanup & Tools
Levi Krein
Associate Professor CIS
What is a head crash?


Occurs when read/write head touches platter surface
Spinning creates cushion of air that floats read/write head above platter


Clearance between head and platter is approximately two-millionths of an inch
A smoke particle, dust particle, or human hair could render drive unusable
hair
read/write head
dust
clearance
smoke
platter
Levi Krein
Associate Professor CIS
What is a disk cache?
processor

Portion of
memory that
processor uses
to store
frequently
accessed items
disk cache
first request
for data—to disk cache
second request
for data—to hard disk
hard disk
Levi Krein
Associate Professor CIS
What are external hard disks and removable hard disks?

Used to back up or transfer files
External hard disk — freestanding
hard disk that connects to system unit
Removable hard disk — hard disk
that you insert and remove
from hard disk drive
Hard drive is
designated as
drive C
Levi Krein
Associate Professor CIS
What is a miniature hard disk?



Provide greater storage capacities than flash memory
Smaller than notebook computer hard disks
A pocket hard drive is a self-contained unit
Levi Krein
Associate Professor CIS
Magnetic Disks – What is a disk controller?

Chip and circuits that control transfer of data from disk
SATA (Serial Advanced
Technology Attachment) controller
uses serial signals to transfer data,
instructions, and information
SCSI
controller supports up to fifteen
devices including hard disks, CD
and DVD drives, tape drives,
printers, scanners, network cards
EIDE (Enhanced Integrated Drive
Electronics) controller supports four
hard disks, provides connections for
CD and DVD drives
SAS
controller supports many connected
devices at once, including hard disks,
CD and DVD drives, printers,
scanners, digital cameras, and more
What is online storage?


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
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Service on Web that provides storage for minimal monthly fee
Files can be accessed from
any computer with Web
access
Large files can be downloaded
instantaneously
Others can be authorized
to access your data
Offsite backup of data
Video
Levi Krein
Associate Professor CIS
Magnetic Disks – What is a floppy disk?

Portable, inexpensive storage
medium (also called diskette)
Obsolete?
Thin, circular, flexible film enclosed
in 3.5” wide plastic shell
Optical Discs = CDs and DVDs
Push the button to
slide out the tray.



Flat, round, portable
metal discs with
protective plastic
coating
Can be read only or
read/write
Most PCs include an
optical disc drive
Insert the disc,
label side up.
Push the same button
to close the tray.
Disc: Alternative spelling of disk . Disc is often
used for optical discs, while disk generally
refers to magnetic discs, but there is no real
rule.
Levi Krein
Associate Professor CIS
How does a laser read data on a CD or DVD?
Link to “How
CDs Work”
disc label
lens
pit
0
prism
Step 1.
Laser diode
shines a light
beam toward
disc.
laser
diode
lightsensing
diode
lens
land
Step 3.
Step 2.
If light strikes
a pit, it scatters.
If light strikes a
land, it is
reflected back
toward diode.
1
prism
laser
diode
lightsensing
diode
Reflected light is
deflected to a
light-sensing diode,
which sends digital
signals of 1 to
computer. Absence
of reflected light is
read as digital
signal of 0.
Levi Krein
Associate Professor CIS
How is data stored on a CD or DVD?


Typically stored in
single track
Track divided
into evenly
sized sectors
that store
items
single track
spirals to edge
of disc
disc sectors
Levi Krein
Associate Professor CIS
What is a CD-ROM?




Compact disc
read-only memory
Cannot erase or
modify contents

Single-session
Typically holds
650 MB to 1 GB
Commonly used
to distribute
multimedia (music)
and complex
software
Levi Krein
Associate Professor CIS
What is the data transfer rate of a CD-ROM drive?
Original CDs
Transferred at
150 KBps
(kilo bytes per second)
1X
1X
10X
48X
75X
?
10X = 150 x 10
or 1,500 KBps
48X:
48  150 KBps = 7,200 KBps
or 7.2 MBps
75  150 KBps
11,250 KBps
Levi =
Krein
or 12.25 MBps
Associate Professor CIS
What is a Picture CD?
Stores digital
versions of
roll of film
Film developers
offer
Picture CD
service
Can be
modified
using photo
editing software
Step 1.
Step 3.
Drop off film to
be developed.
Mark the Picture
CD box on the
film-processing
envelope.
At home, print images
from Picture CD on
your ink-jet photo printer.
A CD-ROM drive can read a
Picture CD & other CDs
p. 7.19(but
Fig. 7-25
CAN NOT read DVDs)
Step 2.
When you pick up
prints and negatives, a
Picture CD contains
digital images of each
photograph.
At a store, print images to
Picture CD at kiosk.
Levi Krein
Associate Professor CIS
What are CD-Rs and CD-RWs?
Multi-session?
Must have
CD recorder
or CD-R drive
CD-R (compact disc-recordable)
— disc you can write on once
c
Cannot erase
disc’s contents
CD-RW (compact disc-rewritable)
— erasable disc you can write on
multiple times
ce
Must have
CD-RW software
and CD-RW drive
Levi Krein
Associate Professor CIS
What is a DVD-ROM ?
digital versatile disc -ROM or
digital video disc -ROM?
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High capacity disc capable of
storing 4.7 GB to 17 GB
Must have DVD-ROM drive or
DVD player to read DVD-ROM
Stores databases, music,
complex software, and movies
DVD
DVD drive
Levi Krein
Associate Professor CIS
DVDs

Blu-ray discs storage capacity = 100 GB
 Blu-ray has won the high definition
storage medium for movies

HD-DVD discs lost out to Blue-ray

HD-VMDs have storage capacity of up to
40 GB or more
 Competitor to Blu-ray
 20 layers

UMD can store up to 1.8 GB
 Mini-DVD; PlayStation Portable
Levi Krein
Associate Professor CIS
How does a DVD-ROM store data?
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Two layers of pits are used, lower layer is
semitransparent so laser can read through
Some are double-sided
Data is packed (pits are closer together) more densely
DVD-RW is a rewritable DVD
 It can write on CD-R, CD-RW, DVD-R & DVD-RW
Levi Krein
Associate Professor CIS
What is tape?

Magnetically coated plastic ribbon
capable of storing large amounts
of data at low cost
 Sequential access, like music

Primarily used for backup
Sequential access is the opposite of Direct access —
used on hard disks, CDs, and DVDs — which can locate
particular item immediately
Levi Krein
p. 7.24 Fig. 7-29
Associate Professor CIS
What is a PC Card?


Adds capabilities to computer
Credit-card-sized device commonly
used in notebook computers
Levi Krein
Associate Professor CIS
What is miniature mobile storage media?

Storage for small mobile devices
CompactFlash
Secure Digital
Memory Stick
xD Picture Card
Miniature
mobile storage
media
Levi Krein
Associate Professor CIS
What is a card reader?


Reads information stored on miniature mobile storage media
Type of card determines type of card reader needed
Levi Krein
Associate Professor CIS
What is a USB Flash Drive?

Plugs in a USB port on a
computer or mobile device

Storage capacities up to 64 GB
How flash drives are made.
Check out the robotics.
8 minutes
Levi Krein
Associate Professor CIS
What is a smart card?

Stores data on microprocessor
embedded in small card

Input, process, output, and
storage capabilities

Sometimes called intelligent
smart card
Prepaid telephone
cards
Levi Krein
Associate Professor CIS
What are microfilm and microfiche?
Store microscopic images of
documents on roll or sheet of film
Microfilm — 100- to
215-foot roll of film
Microfiche — small sheet of
film, usually 4”  6”
Levi Krein
Associate Professor CIS
How do life expectancies of various media compare?

Microfilm and microfiche have longest life of any storage media
Levi Krein
Associate Professor CIS
Drive Letter Designations
Floppy Disks
Drive Letter A & B
Hard Disks
Drive Letter C
More Hard Disks = D, E, etc.
Optical Drives
Next available letter after
hard disks
Flash Drives
Next available letter after
optical drives
Levi Krein
Associate Professor CIS
Other Storage Devices
View Video
Dogtags
Levi Krein
Associate Professor CIS
Other Storage Devices
Storage Cube
View Video
Notice Floppy Disks and Magnetic Tape
Levi Krein
Associate Professor CIS
Summary of Storage
Chapter 7 Completed
Levi Krein
Associate Professor CIS