Lesson 3: Working with Storage Systems
• storage systems
• hard disk drives
• optical drives
• portable or removable storage devices
• network drives
• remote storage
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What Are Storage Systems?
• RAM is temporary so you must save work to storage
device
• Storage device you use depends on amount of storage
you need and speed of data retrieval or data transfer rate
• Hard disk drives used most often to store and retrieve
software programs and data
• Can use other media such as flash drive or optical disc for
backup or portability purposes
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Working with Disk Drives
• Disk drive performs three functions:
− Rotates disk at constant speed to access sectors on entire disk
surface
− Moves read/write head across tracks on entire disk surface
− Reads data from disk and writes data to disk using read/write head
• Data from RAM written on disk arranged in tracks divided
in sectors
• Process of preparing disk for use is called formatting
− Places special information on each track that marks location of
each sector
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Working with Hard Disk Drives
• Primary storage area for both data and programs
− Software programs must be installed on hard drive
− Hard drive stores and retrieves information at high speeds
• Data transfer rate (throughput) of hard drive is function of
hard drive rotation speed and number of heads per surface
− The higher the rotation speed and/or number of heads,
the less time it takes to find data
− Range in capacity from 100 MB to 100+ GB
− Also used in network servers where drives very large to
accommodate requirements of whole organization and data
storage requirements
− Data transfer rate quite fast although can be restricted by type of
network interface cards and number of users or tasks to be processed
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Working with Optical Drives
• Designed to read flat, circular disc, commonly referred to as
Compact Disc (CD) or Digital Versatile/Video Disc (DVD)
− Read by laser device or optical drive that spins disc at speeds from
200 rpm or higher
• CD-ROM (Compact Disc Read Only Memory) or DVD-ROM
drive
− Similar to player in audio/video entertainment system
− Information written or burned onto surface and retrieved with laser
beam
− Can only read data
• New computers come with at least one optical drive
− Usually DVD optical drive or CD/DVD optical writer drive.
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Optical Writers
• Also known as burner drive, looks and acts like regular optical disc
drive
− Software comes with optical writer drive to “burn” or write data onto a disc
• Formats of drives include:
− CD-R/ DVD-R: can write once only to blank disc, but disc can be read
multiple times
− CD-RW/ DVD-RW: can read and write multiple times onto same disc
− DVD-RAM: similar to DVD-RW but can only be used on devices that
support this format; usually in the form of cartridges
• Blank discs relatively inexpensive, with -R disks cheaper than -RW
• Size of disc can be 650 or 700 MB, while DVDs can be 4.7GB to
17+GB with rapid access speeds
• Special software needed to manipulate or edit video before burned to
DVD
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Using Other Types of Storage Devices
• Tape drive or tape streamer uses cartridge with magnetic tape
− Generally used to back up large amount of data
− Use different formats, with tape sizes ranging from 250MB to over 80GB
− Other tape drives use Digital Audio Tape (DAT) format
• Zip drive similar to DVD-RAM drive except that disk can hold
between 100MB and 750MB data
− Offers relatively inexpensive storage option
− Newer systems not compatible with original 100MB devices
• Removable media systems can include flash memory cards,
sticks or USB flash key/thumb drives, or external hard drives
− Benefits include portability, large storage size, and data-sharing capability
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Using Other Types of Storage Devices
• Hard drives in network server similar to hard disk drives in
computer
− Traditionally much larger than available with desktop computer
− May be set as disk array, as drives usually organized to work
together
• Remote or virtual storage systems do not exist on your
computer or location
− Common service provided by Internet Service Providers (ISP)
− Drives on network or dedicated server at particular site
− Must login to with secure ID and password to access information
− Very useful for off-site backup storage of data, or as “central
system” for people in multiple locations to share information
− Disadvantage can be speed of Internet connection
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