Distinguish between primary and secondary storage. Discuss the important characteristics of secondary storage, including media, capacity, storage devices, and access speed. Describe hard disk platters, tracks, sectors, and head crashes. Compare internal and external hard drives. Discuss performance enhancements including disk caching, RAID, file compression, and file decompression.

Define optical storage including compact, digital versatile, and high-definition discs. Define solid-state storage, including solid-state drives, flash memory, and USB drives. Define cloud storage and cloud storage services. Discuss mass storage devices, enterprise storage systems, and storage area networks.

Data storage has expanded from text and numeric files to include digital music files, photographic files, video files, and much more. These new types of files require secondary storage devices with much greater capacity. In this chapter, you learn about the many types of secondary storage devices including their capabilities and limitations.

Secondary storage characteristics Primary storage Volatile storage Temporary storage Random Access Memory (RAM) Secondary storage Nonvolatile storage Permanent storage 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 Writing– process of saving information to the secondary storage device Reading – process of accessing information from secondary storage

Provides permanent or nonvolatile storage Data and programs can be retained after the computer has been shut off Most desktop microcomputer systems have both hard and optical disk drives Optical disks – large storage capacity (Key Term) Hard disk – large storage capacity and fast retrieval times

Store and organize files using tracks, sectors, and cylinders Use rigid, metallic platters that are stacked one on top of one another Store and organize files using tracks, sectors, and cylinders Large capacity (terabytes) Susceptible to head crash Two types of hard disks: Internal Hard Disk External Hard Disks Performance enhancements Composed of metallic rather than plastic disks Platters – rigid metallic, stacked one on top of another Track-rings of concentric circles Each track is divided into wedge-shaped sections called sectors A cylinder (Key Term) runs through each track of a stack of platters Fast information storage and retrieval

Occurs when read-write head makes contact with the hard disk’s surface or with particles on its surface Disastrous Read-write head is .000001 inch above surface Return

Located inside system unit and often designated as the C: drive Used to store programs and data files Advantages over removable media Capacity Access speed Located inside the system unit Used for storing the operating system, other programs, and large data files You should perform routine maintenance and periodically backup all important files Return

Removable hard disks Used to complement internal hard disk with an unlimited amount of additional storage Connect to a USB or FireWire port Used to complement internal hard disk. Return

Disk caching to improve hard disk performance Redundant arrays of inexpensive disks (RAID) to expand storage and to improve access speed File compression and decompression to increase capacity 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 (Key Term) 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 is a well-known program, and you can also use utility programs in Windows. Return

Hold over 100 gigabytes (GB) of data Attributes Lands Pits Three types Compact Disc (CD) Digital Versatile Disc (DVD) Blu-Ray (Hi-Def) Disc Use laser technology. CD (Key Term) and DVD (Key Term) are optical disk formats. Compact, high capacity form of permanent storage (up to 50 gigabytes of data) Optical discs are read by an optical disc drive 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 Rotational speed determines how fast data can be transferred from the CD Optical disks come in many different sizes Most common is 4 ¾ inches Stored in a protective case called jewel boxes

Optical format Capacity of 650 MB to 1 GB Rotation speeds vary Three basic types Read only (CD-ROM) Write once (CD-R) Rewriteable (CD-RW) 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) Used to archive data or to record music downloaded from the Internet Rewriteable: CD-RW Known as erasable optical disks (Key Term) Can be changed Used to create and edit multimedia presentations Ideal for use as permanent data archives for essential company information Return

Like CDs, but newer format called digital versatile disc or digital video disc (DVD) Capacity of 4.7 GB to 17 GB Three basic types Read only (DVD-ROM) Write once (DVD+R and DVD-R) Rewriteable (DVD+RW, DVD-RW, and DVD-RAM) Return

Next generation optical disc for recording high-definition (hi def) video Capacity of 25 GB to 128 GB Blu-ray optical drives are usually capable of reading standard DVDs and CDs in addition to Blu-ray discs Blu-ray, also known as BDs Have a capacity of 25 to 128 gigabytes Blu-ray has seemingly won the battle as the standard high definition video disc Like CDs and DVDs, Blu-ray has three basic types: read only, write once, and rewritable. Return

Solid–state drives (SSDs) No moving parts Faster and more durable than hard disks Flash memory cards Widely used in computers, cameras, and portable devices such as mobile phones and GPS navigation systems USB Drives (or Flash Drives) Connect to USB port Capacity of 1 GB to 256 GB Solid state drives are faster and more durable (no moving parts) than hard drives Require less power Contain solid state memory instead of magnetic disk to store data Used for tablet PCs, like the iPad Flash memory cards are one type of solid state device. Used in digital cameras, ipods

Cloud computing is where the Internet acts as a “cloud” of servers Applications provided as a service rather than a product Supplied by servers Google Apps Mint.com The processing power of the service provider’s server is used to run the applications and your computer is responsible only for displaying the results. The applications and data can be accessed from any Internet-ready device. This means that devices with little storage, memory, or processing power, such as mobile phones, can run the same powerful applications as a desktop computer. Cloud servers provide storage, processing, and memory. Software installation and upgrades are avoided.

Using a cloud storage service makes it easy to upload and share files with anyone.

Large amounts of secondary storage called mass storage An enterprise storage system strategy ensures efficient and safe use of data across an organizational network Devices include: File servers Networked attached storage (NAS) RAID systems Tape libraries Organizational cloud storage Mass storage devices that support enterprise storage systems are File servers (Key Term) – dedicated computer with very large storage capacities that provide user access to fast storage and retrieval of data Network attached storage (NAS) – similar to a files server except less expensive RAID systems (Key Term) – larger versions of the specialized devices discussed earlier in this chapter that enhance organizational security by constantly making backup copies of files moving across the organization’s networks Tape library (Key Term) – device that provides automatic access to data archived on a large collection or library of tapes Organizational cloud storage – high speed internet connection to a dedicated remote organizational cloud storage server.

Architecture to link remote computer storage devices, such as enterprise storage systems, to computers such that the devices are available as locally attached drives User’s computer provides file system, but SAN provides disk space House data in remote locations and still allow efficient and secure access

General employer requirements Software engineers analyze users’ needs and create application software General employer requirements Bachelors degree in computer science Extensive knowledge of computers and technology Communication and analytical skills Annual salary of $63,000 to $98,500

Future secondary storage disks will eventually store terabytes (TB) or petabytes (PB) Your entire life captured in digital video on a single disc Currently developing programs that can scan photos and videos for a particular person’s face Are there downsides? Could your personal video log be used to incriminate you in a court of law? Could someone else’s video log be an invasion of your right to privacy?

Compare primary storage and secondary storage and discuss the most important characteristics of secondary storage. Discus hard disks including density, platters, tracks, sectors, cylinders, head crashes, internal, external, and performance enhancements. Discuss optical disks including pits, lands, CDs, DVDs, Blu-ray, and hi def. Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements

Discuss cloud computing and cloud storage. Discuss solid-state storage including solid-state drives, flash memory, and USB drives. Discuss cloud computing and cloud storage. Describe mass storage devices including enterprise storages systems, file servers, network attached storage, RAID systems, tape libraries, organizational cloud storage, and storage area network systems. Have students turn to the end of Chapter 8 in their textbooks to view the same “Open-Ended” questions/statements