Storage
- Storage holds data, instructions and information for future use- 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
- 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
- Access time measures:
- The amount of time it takes a storage device to locate an item on a storage medium
- The time required to deliver an item from memory to the processor
Hard Disk
- It contains one or more inflexible, circular platters that use magnetic particles to store data, instructions and information- It can store data using longitudinal recording or perpendicular recording
- Characteristics:
- Capacity
- Platters
- read/Write heads
- Cylinders
- Sectors and tracks
- Revolutions per minute
- Transfer rate
- Access time
- A head crash occurs when a read/write head touches the surface of a platter
- Always keep a backup of your hard disk
- Network attached storage (NAS) device is a server connected to a network with the sole purpose of providing storage
- External hard disk is a separate free-standing hard disk that connects to your computer with a cable or wirelessly
- Removable hard disk is a hard disk that you insert and remove from a drive
- Internal and external hard disks are available in miniature sizes
- 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
- It is 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
- ExpressCard module is a removable device that fits in an ExpressCard slot
Cloud Storage
- It is an Internet service that provides storage to computer users
- Access files from any computer
- Store large files instantaneously
- Allow others to access their files
- View time-critical data and images immediately
- Store offsite backups
- Provide data center functions
Optical Disc
- It consists of a flat, round, portable disc made of metal , plastic and lacquer that is written and read by a laser- It stores software, data, digital photos, movies and music
- 2 types of optical disc:
- Read only
- rewritable
- track is divided into evenly sized sectors
- Store the disc in a jewel box when not in use
- Hold a disc by its edges
- Do not eat, smoke or drink near a disc
- Do not expose the disc to excessive heat or sunlight
- Do not stack discs
- Do not touch the underside of the disc
- CD-R is a multisession optical disc on which users can write, but not erase
- CD-RW is an erasable multisession disc
- Archive disc stores photos from an online photo center with a cost
- Picture disc is CD-ROM that stores digital versions of film
- DVD-ROM is a high-capacity optical disc on which users can read but not write
- Blu-ray Disc-ROM (BD-ROM) has a storage capacity of 100 GB
- DVD-RW, DVD+RW and DVD+RAM are high-capacity rewritable DVD formats
Other Types of Storage
- Tape - is a magnetically coated ribbon of plastic capable of storing large amounts of data and information
- Tape driver reads and writes data and information on a tape
- Magnetic stripe card - contains a magnetic stripe that stores information
- Smart card - stores data on a thin microprocessor embedded in the card
- Microfilm and microfiche - store microscopic images or documents on a roll or sheet film
- Enterprise storage - stores huge volumes of data and information for large businesses
- Uses special hardware for heavy use, maximum availability and maximum efficiency
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