Chapter 8 Types of Storage

• Differentiate between storage devices and storage media
• Describe the characteristics of an internal hard disk including capacity, platters, read/write heads, cylinders, sectors and tracks, revolutions per minute, transfer rate, and access time
• Discuss the purpose of network attached storage devices, external and removable hard disks, and hard disk controllers
• Describe the various types of flash memory storage
• Describe cloud storage and explain its advantages
• Describe the characteristics of optical discs
• Differentiate among various types of optical discs: CDs, archive discs and Picture CDs, DVDs, and Blu-ray Discs
• Identify the uses of tape, magnetic stripe cards, smart cards, microfilm and microfiche, and enterprise storage

Storage

• Storage holds data, instructions, and information for future use
• A storage medium is the physical material on which a computer keeps data, instructions, and information
• Capacity is the number of bytes a storage medium can hold
• A storage device is the computer 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

Hard Disks

• A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information
• Hard disks can store data using longitudinal recording or perpendicular recording
• Characteristics of a hard disk include Capacity, Platters, Read /Write Heads, Cylinders, Sectors and Tracks, Revolutions per Minute, Transfer Rate, Access Time.
• Formatting is the process of dividing the disk into tracks and sectors so that the operating system can store and locate data and information on the disk
• The hard disk arms move the read/write head, which reads items and writes items in the drive
• A head crash occurs when a read/write head touches the surface of a platter
• Always keep a backup of your hard disk
• RAID (redundant array of independent disks) is a group of two or more integrated hard disks
• A network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage
• A disk controller consists of a special-purpose chip and electronic circuits that control the transfer of data, instructions, and information from a disk to and from the system bus and other components of the computer

Flash Memory Storage

• Flash memory chips are a type of solid state media and contain no moving parts
• Solid state drives (SSDs) have several advantages over magnetic hard disks :- Faster access time, Faster transfer rates, Generate less heat and consume less power, Last longer
• USB flash drives plug into a USB port on a computer or mobile device
• An ExpressCard module is a removable device that fits in an ExpressCard slot
• Developed by the PCMCIA
• Commonly used in notebook computers

Cloud Storage

• Cloud storage is an Internet service that provides storage to computer users
• Users subscribe to cloud storage for a variety of reasons:

1. Access files from any computer
2. Store large files instantaneously
3. Allow others to access their files
4. View time-critical data and images immediately
5. Store offsite backups
6. Provide data center functions

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
• Typically store software, data, digital photos, movies, and music
• Read only vs. rewritable
• Optical discs commonly store items in a single track that spirals from the center of the disc to the edge
• Track is divided into evenly sized sectors