Discovering Computers
Technology in a World of Computers,
Mobile Devices, and the Internet
Chapter 8
Digital Storage
Storage
A storage medium is the physical material
on which a computer keeps data,
information, programs, and applications
Cloud storage is another storage option, in
which the actual online storage media
used is transparent to the user
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Discovering Computers 2014: Chapter 8
Storage
• A storage device is the hardware that records
and/or retrieves items to and from storage media
Reading is the process
of transferring items
from a storage medium
into memory
Writing is the process of
transferring items from
memory to a storage
medium
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Storage
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Figure 8-1
Storage
• Capacity is the number of bytes a storage medium
can hold
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Table 8-1
Storage
• Items on a storage medium remain intact even
when you turn off a computer or mobile device
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Figure 8-2
Storage
• 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
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Discovering Computers 2014: Chapter 8
Figure 8-3
Hard Disks
• A hard disk contains one or more inflexible, circular platters
that use magnetic particles to store data, instructions, and
information
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Figure 8-4
Hard Disks
• Formatting is the process of dividing the disk into tracks
and sectors
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Figure 8-6
Hard Disks
• A head crash occurs when a read/write head
touches the surface of a platter
• Always keep a backup of your hard disk
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Figure 8-8
Hard Disks
• Disk cache, sometimes called a buffer, consists of
a memory chip(s) on a hard disk that stores
frequently accessed data, instructions, and
information
• The larger the disk cache, the faster the hard disk
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Hard Disks
• RAID (redundant array of independent disks) is a
group of two or more integrated hard disks
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Figure 8-9
Hard Disks
• An external hard disk is a separate freestanding
storage device that connects with a cable to a USB
port or other port on a computer or mobile device
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Discovering Computers 2014: Chapter 8
Figure 8-10
Flash Memory Storage
• Flash memory chips are a type of solid state
media and contain no moving parts
• An SSD (solid state drive) has several advantages
over magnetic hard disks:
Higher storage Faster access Faster transfer
Quieter operation More durable
capacities times rates
Less power Less heat
Lighter weight Longer life
consumption generation
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Discovering Computers 2014: Chapter 8
Flash Memory Storage
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Discovering Computers 2014: Chapter 8
Figure 8-11
Flash Memory Storage
• A memory card is a removable flash memory
device that you insert and remove from a slot in a
computer, mobile device, or card reader/writer
CF SDHC SDXC miniSD microSD
xD Picture Memory Stick
microSDHC microSDXC M2
Card PRO Duo
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Flash Memory Storage
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Figure 8-12 Discovering Computers 2014: Chapter 8
Flash Memory Storage
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Figure 8-13
Flash Memory Storage
• USB flash drives plug into a USB port on a
computer or mobile device
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Figure 8-14
Cloud Storage
• Cloud storage is an Internet service that provides
storage to computer or mobile device users
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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
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Figure 8-15
Optical Discs
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Figure 8-16
Optical Discs
• Optical discs commonly
store items in a single
track that spirals from
the center of the disc to
the edge of the disc
• Track is divided into
evenly sized sectors
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Figure 8-17
Optical Discs
A CD-ROM can be A CD-R is an optical
read from but not disc on which users
written to can write once, but
• Single-session disc not erase
A CD-RW is an
erasable
multisession disc
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Optical Discs
A DVD-ROM is a high-capacity optical disc on which users
can read but not write on or erase
A DVD-R or DVD+R are competing DVD-recordable WORM
formats, on which users can write once but not erase
DVD-RW, DVD+RW, and DVD+RAM are high-capacity
rewritable DVD formats
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Discovering Computers 2014: Chapter 8
Enterprise Storage
• Enterprise hardware allows large organizations to
manage and store data and information using
devices intended for heavy use, maximum
efficiency, and maximum availability
– RAID duplicates data, instructions, and information to
improve data reliability
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Figure 8-19
Enterprise Storage
• Network attached storage (NAS) is a server that is
placed on a network with the sole purpose of
providing storage to users, computers, and
devices attached to the network
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Figure 8-20
Enterprise Storage
• A storage area network (SAN) is a high-speed
network with the sole purpose of providing
storage to other attached servers
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Figure 8-21
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
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Figure 8-22
Other Types of Storage
• A magnetic stripe card contains a magnetic stripe
that stores information
• A smart card stores data on an integrated circuit
embedded in the card
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Figure 8-24
Other Types of Storage
• The RFID tag consists of an antenna and a memory chip
that contains the information to be transmitted via radio
waves
• An RFID reader reads the radio signal and transfers the
information to a computer or computing device
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Figure 8-25
Other Types of Storage
• Microfilm and microfiche store microscopic
images of documents on a roll or sheet film
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Figure 8-26
