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Chapter 4 Second Storage, image, image, image, image, image, image -…
Chapter 4 Second Storage
STORAGE
- Holds data, instruction and information for future use
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Storage medium
- the physical material on which a computer keeps data, instructions and information.
Storage device
- The computer hardware that records and/or retrieves items to and from storage media
- involves two processes reading and writing
Secondary Storage
- Provides permanent or nonvolatile storage.
- Items on a storage medium remain intact even when you turn off a computer or mobile device..
HARD DISK - contains one or more inflexible, circular platters that use magnetic particles to store data, instructions and information.
Tracks - concentric rings on the platter.
Sectors - wedge-shaped sections.
Cylinders - run through each track of a stack of platters.
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Internal hard disk
- Located inside the system unit
- Fast access to retrieve large quantities of information
- Cannot be easily removed from the system unit
External Hard Disk
- Slower access
- Usually connected to a USB or Thunderbolt port on the system unit
- Easily removed
Performance Enhancements
- Disk caching
:check: Uses cache and anticipates data needs
- RAID
:check: Linked, inexpensive hard disk drives
- File compression and decompression
:check: Reduce file size & expands compressed files
SOLID-STATE STORAGE
- contains no moving parts
- Data & information are stored and retrieved electronically.
- Types of flash memory storage:
Solid-state drives
- Faster and more durable than hard disks
- Access to slash memory or solid state storage
Flash Memory Cards
- Widely used in laptops, smartphones, GPS navigation system.
USB Drives (or Flash Drives)
- Connect to USB port
- Capacity of 1 GB to 256 GB
- Portable
CLOUD STORAGE
- Is an Internet service that provides storage to computer or mobile device users
- Supplied by servers that provide cloud storage or online storage.
- Advantages for users include less maintenance, fewer hardware upgrades, and easy file sharing and collaboration.
- Disadvantages for users include slower access speed and less control over file security.
OPTICAL DISCS
- Consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser
Compact discs (CDs) were the first; typical storage 700MB, often used to store music.
Digital versatile discs (DVDs) are standard optical discs, typical storage 4.7 GB and often used to store movies and software.
Blu-ray discs (BDs) are the newest; designed to store hi-def (high-definition) video; typical storage 25 GB; often to store hi-def video and video games.
Each of these optical discs has three basic formats:
- Read-only (ROM for read-only memory) discs cannot be written on or erased by the user.
- Write-once (R for recordable) discs can be written on once. After that, they can be read many times but cannot be written on or erased.
- Rewritable (RW for rewritable or RAM for random-access memory) discs are similar to write-once discs except that the discs surface is not permanently altered when data is recorded.
MASS STORAGE DEVICES
- Refers to the tremendous amount of secondary storage required by large organizations.
- Mass storage devices are specialized high-capacity secondary storage devices.
- Enterprise storage system is most large organizations have established a strategy called and to promote efficient and safe use data.
- Mass storage devices that support this strategy are file servers, network attached storage (NAS), RAID systems, and organizational cloud storage.
- A storage are network (SAN) is a method of using enterprise-level remote storage systems as if they were local to your computer.
CAREERS in IT
- Disaster recovery specialists are responsible for recovering systems and data after a disaster strikes an organization. Bachelor's or associate's degree in information systems or computer science, experience, and additional skills in the areas of networking, security and database administrations are desirable. Salary range is $73000 to $92000
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