Hard drives
From TSG Library of Knowledge
A hard drive is used in computers to save information. A hard drive is comprised of a magnetic disc that rotates and is read by a head. Most computers have only one internal hard drive, but it is not uncommon to see an external hard drive used for additional storage or as a backup.
There are several styles of internal hard drives, varying in interface type, storage capacity, speed (RPM), and buffer size.
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Interface Types
IDE (aka Ultra ATA or PATA) , SCSI , SATA and SATA-II , SAS (Serial Attached SCSI)
Storage Capacity
A hard drive's capacity is usually measured in Gigabytes (GB), but also occasionally as GiB. Most new computers come with a hard drive of at least 100GB, which is more than enough for most computer users. Even so, it is not uncommon to see hard drives as big as 500GB in new computers, and drives up to 1.5TB, or terabyte are sold.
When comparing hard drive density, it is important to note the difference in which companies might market or recognize hard drive size. Manufacturers generally use the decimal format, in which 1GB = 1 billion bytes (1,000,000,000 bytes) whereas Microsoft and other operating systems generally use a binary system, such that 1GB is 1,073,741,824, and a Manufacturer's 1GB rated hard drive will be reported as a roughly 930MB drive.
Speed (RPM)
In addition to capacity, hard drives are also rated by how quickly they can rotate the magnetic media. This is rated in Rotations Per Minute (RPM). Most desktop hard drives are 7200RPM, while most notebook hard drives are 5400RPM. High-end computers and servers usually have hard drives that run at 10,000RPM or 15,000RPM. Obviously, the higher the RPM, the better.
Buffer Size
Buffer size refers to memory built directly onto the hard drive for rapid access and storage. Common sizes range from 2MB to 16MB on modern drives. A Higher cache generally improves burst read/ write speeds.
Solid State Hard Drives
Unfortunately, because the hard drive has the only moving parts in the computer, it is also one of the most frequent to fail. A new technology, called Solid State, is a hard drive with no moving parts. It works similar to USB Flash Drives, which use memory chips rather than a moving magnetic media. There are some downsides to this new technology, including limitations to the number of reads and writes, but the biggest limitation today is that they are too expensive to be included in most computers. Apple's new light notebook, the Air, is one exception and is available with a Solid State Hard Drive.
As memory saturation becomes more intense and seek speeds of firmware rapidly increase, then solid-state "hard-drives" will become the industry standard.
Additionally, as local operation moves increasingly to a virtual presence (e.g.s Virtualization and The Cloud), local data storage will rapidly become redundant.
For many reasons, local processing power and data storage are already a technology of the past: PCs and Laptops will migrate to moving almost every application function to remote facility: thus the need to employ massive number-crunching CPUs and local storage (Whether dedicated HDD, Firmware - such as Solid State HDDs - or electro-mechanical devices), will rapidly evaporate.
The standalone PC will transmute into a "Back to the Future" clone of the old Semi-Smart workstations, which were rolled out on Mini-Computer netowrks, using the original Ethernet for LANS (local Area Networks).
Continual downsizing meant PC architecture supplanted LANS and migrated to Client-Server Networks: faster ADSL offering greater bandwidth, allows distributed broadband, globally and all a terminal needs is a browser: with minimal local CPU processing power and limited local data storage to support this.
Thus the workstation or PC or laptop/notebook/pda of the near future will function on a series of web apps and applets: rather than the user having to purchase both Operating System and Application Software Suites as at present.
Useful Software
Most hard drive manufacturers allow you to download software that allows you to clone your hard drive or check it for errors. A free program called HDD Health is available for Windows and will check your hard drive's SMART status and alert you if a failure is imminent.
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