1. 8 SECONDARY STORAGE CHAPTER
Secondary storage devices are used to save, to back up, and to transport files
Over the past several years, data storage capacity has expanded from saving numbers and text to include digital images and video
Competent end uses need to know the capabilities, the limitations, and the uses of floppy disks, hard disks, optical disks, and other types of secondary storage

2. Competencies (Page 1 of 2)
Distinguish between primary & secondary storage
Describe the traditional floppy disk and compare it to high capacity floppy disks
Compare internal hard disks, hard-disk cartridges, and hard-disk packs
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3. Competencies (Page 2 of 2)
Describe ways to improve hard-disk operations, including disk caching, redundant arrays of inexpensive disks, and data compression and decompression
Discuss the different types of optical disks; mass storage
Describe solid-state storage, Internet drives, and magnetic tape
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4. Storage RAM Primary storage Secondary storage
Volatile
Temporary
Secondary storage
Nonvolatile
Permanent
Secondary storage characteristics
Media
Capacity
Storage devices
Access speed
Secondary storage permanently saves information for future use; to share information with others; to modify at later date
Secondary storage is nonvolatile – stores programs and data as opposed to temporary storage (RAM)
Characteristics include:
Media or medium – actual physical materials that holds the data and programs
Capacity – measures how much a particular storage medium can hold
Storage devices – hardware that reads data and programs from storage media (most also write to storage media)
Access speed or access time – measures the amount of time required by the storage device to retrieve data and programs
RAM
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5. Secondary Storage Devices
Most desktop microcomputer systems have floppy disks, hard disks, and optical disk drives
Floppy disk – inexpensive and removable
Optical disks – large storage capacity
Hard disk – large storage capacity and fast retrieval times
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6. Traditional Floppy Disk
Also known as:
Diskettes
Floppies
Portable storage media
Floppy disk drives (FDD)
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Floppy disks are removable storage media. Today’s standard is 1.44 MB. Data recorded in rings called called tracks; tracks divided into wedge-shaped sections called sectors
Most disks manufactured currently preformatted w/tracks and sectors
While called floppy, actually pieces of flat Mylar rotating within a hard plastic jacket
The bits of data are represented by the presence or absence of magnetic charges
Storage capacities range from 360 KB to 1.44 MB
Write-protect notch or window to prevent inadvertent erasure or write-over
Density refers to how tightly the bits can be packed next to one another; common density is 2HD
A shutter on the disk slides to the side to expose the recording surface
Labels provide an area to write or document the contents of the disk
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7. High Capacity Floppy Disks
Known as a floppy-disk cartridge
Require special disk drives
Three well known types
Zip disks
HiFD disks
SuperDisks
Zip disks – usually manufactured by Iomega; 100 MB, 250 MB, or 750 MB worth of storage; requires own drive
HiDF disks – usually manufactured by Sony Corp; 200 MB or 750 MB capacity
Biggest advantages: can use HiDF disk in floppy drive; popular with notebooks
Super disks – usually manufactured by Imation; 120 MB or 240 MB capacity; SuperDisk disk drives can use standard floppy disks
Zip disks – 100 MB, 250 MB or 750 MB
HiFD disks MB or 720MB
SuperDisks – 120 MB or 240 MB
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8. Hard Disks Use thicker, metallic platters for storage
Faster than a floppy diskette
Large capacity
Sensitive instruments
There are three types of hard disks:
Internal
Hard-disk cartridge
Hard-disk pack
Composed of metallic rather than plastic disks
Platters – rigid metallic, stacked one on top of another
Fast information storage and retrieval
Read-write head is inch above surface
An internal hard disk is also known as a fixed disk
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9. Internal Hard Disk Located inside system unit Known as a fixed disk
Designated as the C drive
Advantages over floppies
Access speed
Capacity
Located inside the system unit; also known as fixed disk
Used for storing the operating system, other programs, and large data files
You should perform routine maintenance and periodically backup all important files
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10. Hard-Disk Cartridges Removable hard disks
Used to complement internal hard disk
Capacities of 10 to 20 GB
Hard-disk cartridge
PC Card Hard Disks
Capacity limited only by number of cartridges; used to complement internal hard disk.
Popular Vendor: Peerless disks from Iomega
PC Card hard disk available for notebooks with a capacity of up to 5 GB
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11. Hard-Disk Packs Removable hard disk Massive storage capacity
Common in mainframes
Resembles stack of vinyl records
Massive storage capacity
Common in mainframe systems
Composed of a larger number of platters, resembling a stack of record albums
Most platters offer read-write surfaces on top and bottom
Access time – time between the computer’s request for data from secondary storage and the completion of the data transfer; usually access time is faster with this type of secondary storage
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12. Hard Disk Performance Enhancements
Disk caching
Redundant arrays of inexpensive disks (RAID)
File compression and decompression
Disk caching
Uses hardware and software to anticipate data needs; performs function similar to RAM caching; improves processing by acting as a temporary high-speed holding area between a secondary storage device and the CPU
Frequently used data is stored in memory; when needed, the access time is much faster
Redundant arrays of inexpensive disks (RAID)
Groups of low cost hard-disk drives grouped together using networks and special software
Performs as a single large-capacity disk; but faster than a single disk of comparable size
Often used by Internet servers and large organizations
File compression and decompression
Increase storage capacity
Reduce space required for storage; reduce up to ¼ of original size
WinZip and PKZip are well-known programs, and you can also use utility programs in Windows XP
RAID storage device
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13. Optical Disks Compact Permanent storage Laser beams reflect off pits
Two common types CD
DVD
Use laser technology. CD and DVD are optical disk formats.
Compact, high capacity form of permanent storage (up to 17 gigabytes of data)
Laser beam writes by creating a pattern of pits (holes) and lands (flat areas) to encode data bits
Laser beams reflect off the pits and lands to read the data
Optical disks come in many different sizes
Most common is 4 ¾ inches
Stored in a protective case called jewel boxes
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14. Compact Disc Optical format From 650 MB to 1 GB capacity
Rotation speeds vary
Types
Read only: CD-ROM
Write once: CD-R
Rewriteable: CD-RW
Picture CDs and Photo CDs
CD stands for compact disc
Standard on most computers; can store from 650 MB up to 1 GB
Speed determines how fast data can be transferred
Read only: CD-ROM
Commercial music CD
Read only means it cannot be written on or erased
Used to distribute large databases and references
Write once: CD-R (CD-recordable)
Known as burners
Used to archive data or to record music downloaded from the Internet
Rewriteable: CD-RW
Known as erasable optical disks
Can be changed
Used to create and edit multimedia presentations
Picture CDs and Photo CDs
Special format developed by Eastman Kodak to store digital images
Two types: Single-session or multisession
Ideal for use as permanent data archives for essential company information
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15. Digital Versatile Disc
Digital Versatile Disk or Digital Video Disk (DVD)
Similar to CDs, but can store more data
Types
Read only: DVD-ROM
Write once: DVD+R; DVD-R
Rewritable: DVD+RW; DVD-RW; DVD-RAM
DVD-ROM
Known as DVD players
Used for videos
DVD-R and DVD+R
Two competing write once formats
Write once format
Used to create permanent archives for large amounts of data and to record videos
DVD-RAM or DVD-RW – rewritable version
DVD-RW
DVD+RW
DVD-RAM
Each format has a unique way of storing data; older DVD players can’t read all formats but the new DVD players can
Rapidly replacing the CD rewritable drives
Use to store video from camcorders and developing large multimedia presentations that include extensive graphics and video
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16. Other Types of Secondary Storage
Solid-state storage
Internet hard drives
Magnetic tape
Solid-state storage
No moving parts
Reliable, but expensive
Internet hard drives
Low cost
Flexibility to access information from any location using the Internet
Slower access speed
Magnetic tape
Slower sequential access
Stores data and programs
Used for making backups of data
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17. A Look to the Future Blu-Ray and Plastic Memory Technology
New standard in storage is called Blu-Ray
New disks use blue laser light instead of the red laser light used in traditional CD players
Disks may ultimately hold
Over 50GB on two-sided disks
Equals several movies/TV shows
Help to reduce incompatibility
problems
A new type of storage
Uses tiny plastic prongs that press small dimples onto a plastic sheet; a dimple indicates a 0 and no dimple indicates a 1;
Far great capacity than optical and metallic disks
HDTV broadcasts and streaming audio and video can be recorded on these new disks
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18. Discussion Questions (Page 1 of 2)
Discuss the three most likely successors to the 1.44 MB 3 ½ inch floppy.
What are the three types of hard disks? Describe three ways to improve hard disk performance.
What are the two most common optical disk formats? Describe the basic types for each format.
Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements
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19. Discussion Questions (Page 2 of 2)
Discuss solid-state storage, Internet hard drives, and magnetic tape. What are the advantages and disadvantages of each?
Discuss mass storage, enterprise storage systems, and mass storage devices.
Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements
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