//www.youtube.com/watch?v=Do-O1bou_tA
Primary Storage | Secondary Storage |
Volatile |
|
Temporary Storage | Permanent Storage |
Example : RAM [Random Access Memory] | Media or medium
|
Capacity
| |
Storage devices
| |
Access speed or access time
|
Hard-disk
It is composed of metallic disk. Hard-disk store and organize files using tracks, sectors, and cylinders.
- Platters – rigid metallic, stacked one on top of one another
- Track- rings of concentric circles
- Sector - track which divided into wedge-shaped sections
- Cylinder - runs through each track of a stack of platters
- Clusters - files are allocated space in clusters of sectors
- Fast information storage and retrieval and large capacity [terabytes]
Head crush of hard-disk
Hard-disk is a sensitive instruments. It is easily lead to head crush that may caused by smoke particle, fingerprint, dust, or human hair. It is disastrous case for hard-disk. Head crush occurs when read-write head makes contact with the hard disk’s surface or with particles on its surface. This may cause the data destroyed or loss.
Two types of hard disks
1. Internal Hard Disk
As "internal" means, this kind of hard-disk is located inside the system unit. Commonly, we know it as C: drive.
It is used for storing the operating system, large data files and other programs. It should keep routine maintenance and periodically backup all important files by users.
2. External Hard Disks
As "external" means, it is removable hard-disk. It is used to complement internal hard disk with an unlimited amount of additional storage. Commonly, it is connect to a USB or FireWire port.
Performance Enhancements of hard-disk
1. Disk caching
- Improve hard-disk performance
- Uses hardware and software to anticipate data needs as performs function similar to RAM caching
- Act as a temporary high-speed holding area between a secondary storage device and the CPU to improves processing
- Access data in memory is faster
2. 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
- Faster than a single disk of comparable size
- Often used by Internet servers and large organization to improve access speed and expand storage
3. File compression and decompression
- Increase storage capacity
- Reduce space required for storage
- Example : WinZip and utility programs in Windows
Optical Disks
- Permanent storage which are compact, and high capacity
- Use laser technology
- 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
Three types of optical disks
1. Compact Disc [CD] - Standard on most computers, can store from 650 MB up to 1 GB
a. Read only: CD-ROM
- Commercial music CD
- Read only and cannot be written on or erased
- Used to distribute large databases and references
b. CD-R [CD-recordable]
- Write once
- Used to archive data or to record music downloaded from the Internet
c. CD-RW
- Erasable optical disks
- Rewriteable - Can be changed
- Used to create and edit multimedia presentations
2. Digital Versatile Discs [DVD] - Capacity of 4.7 GB to 17 GB
a. DVD-ROM [Read only]
b. DVD+R and DVD-R [Write once]
c. DVD+RW, DVD-RW, and DVD-RAM [Rewriteable]
3. Blu-ray Disc [BD]
- Used 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 disc also has three basic types: read only, write once, and rewritable
Solid-state Storage
- Require less power
- Solid state drives are faster and more durable [no moving parts] than hard drives
- Contain solid state memory to store data
- Used for tablet PCs [iPad]
- Flash memory cards - Widely used in computers, cameras, and portable devices such as mobile phones and GPS navigation systems
- USB Drives / Flash Drives - Connect to USB port and have capacity of 1 GB to 256 GB
Mass Storage Devices
- Large amounts of secondary storage
- In enterprise storage systems, mass storage devices is used to ensures efficient and safe use of data across an organizational network.
- File servers – very large storage capacities that provide user access to fast storage and retrieval of data
- Network attached storage [NAS] – function similar to file server but less expensive than file server
- RAID systems – constantly backup copies of files moving across the organization’s networks [organizational security]
- Tape library – device that provides automatic access to data archived on a large collection or library of tapes
- Organizational cloud storage – high speed internet connection [remote organizational cloud storage server]
Storage Area Network
- SAN are link remote computer storage devices [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
Updated on 16 December 2018, 12:58 PM; 516 page visits from 9 December 2018 to 7 September 2022
How are hard disks organized?
What is track and sector in hard disk?
What differentiates files stored on the same track and sector?
Which of the following is true about internal hard disk?
Q. | Which of the following statements about the hard disks is TRUE? |
B. | hard disks are considered volatile storage devices |
C. | with the rise of flash drives, hard disks are becoming legacy technology |
D. | hard disks are considered nonvolatile storage devices |
Answer» d. hard disks are considered nonvolatile storage devices |