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Computer Drives

What is A Drive?

The term Drives covers a multitude of devices. These devices are non-volatile in that data written to a drive, unlike RAM, is persisted after the power is pulled from the PC (-assuming, of course, that the write completed prior to the power being dropped).

[Drives] are non-volatile in that data written to a drive, unlike RAM, is persisted after the power is pulled ..

Reading and writing data from a hard drive is much slower than from RAM, partly because the drive needs to physically seek to the correct sector on the disc and read it (-i.e. there is some physical movement needed before the read/write can even start) and partly because RAM is more tightly coupled to the CPU via the Memory Controller Hub (-aka Northbridge) chip.


Different Types of Drive

There are five basic drive types currently available:

  • Hard Drive: this is a magnetic media device. It is the traditional non-volatile storage used by computers and is reasonably fast, able to store vast amounts of data and very competitive price-wise per Gb of storage. Hard drives can differ hugely in performance, so check the read and write speeds for your selected drive before purchase

  • CD-ROM, DVD ROM, BluRay Player: these are all read-only, optical devices (-i.e. they use lasers to read the pits and lands on the surface of a disc) : the difference being the speed they run and amount of data on the disc. These are generally a lot faster than a Burner drive, but still relatively slow

  • CD Burner, DVD Burner: these are all read-write, optical devices (-i.e. they use lasers to burn or read the pits and lands on the surface of a disc) : again, CDs and DVDs differ in their speed and amount of data they can get on the disc. Great for backing up data, but very slow

  • SSD (Solid State Device): these are basically non-volatile memory devices containing no moving parts: the computer sees them as a normal hard drive, but they are effectively a special bank of RAM chips that continue to store data even when the power is off. These are the quickest - and most expensive devices - out there, although some are not much quicker than the fastest hard drives (-so beware). They also do not have the capacity to store the amounts of data that hard drives can (yet). They can be likened to a larger, faster, internal version of a USB Memory Stick

  • Hybrid Drive: some manufacturers offer hard drives combined with a limited SSD (-such as Seagate Momentus), to speed up data transfers. This may become an affordable alternative to SSDs for the less well healed..

[SSDs] are the quickest - and most expensive devices - out there, although some are not much quicker than the fastest hard drives ..

The photo below shows two 3.5" hard drives (top and bottom) with a 2.5" SSD in the middle:

A typical 3.5in drive bay

Note: the SATA power cables have been removed for clarity in the picture above (-but the red SATA data cables have been left in).


Choosing a Drive

The good thing with most Motherboards is that you can mix and match a number of drive types in your PC! Each board will differ, but a common number of drive ports is around six: meaning up to six drives can be connected if so desired. The minimum you can get away with is a single hard drive. However, here is some criteria for choosing when to use each type of device:

There are five basic drive types currently available:

  • Hard Drive: for the bulk of your long-term storage or if funds are tight

  • CD-ROM, DVD ROM, BluRay Player: use if you need to load a lot of commercial software or play CDs, DVDs or BluRay discs

  • CD Burner, DVD Burner: use for backing up important data from your other drives

  • SSD: to turbocharge your PC, invest in a small, fast, SSD to contain your operating system and temporary files only: this will cut boot times and tool startup times dramatically. The smaller SSDs (-e.g. 32Gb) are much also more affordable (-the price tends to increase exponentially)!

  • Hybrid Drive: could be a higher speed alternative to the hard drive for the bulk of your data if funds allow or you are limited to a single drive


SATA verses IDE

Drives are connected to the Motherboard using one of two incompatible interfaces:

  • IDE: this is the older, parallel, interface. Nowadays, you would be hard pressed to find much other than CD/DVD Players or burners using this interface; transfer rates are generally slower than with SATA drives (-but not necessarily so)

  • SATA: this is a serial interface that has all but replaced IDE in new builds. Be aware that they are several SATA versions: SATA-1, SATA-2 and SATA-3. SATA-3 is the fastest (600MB/s) and is just appearing on new boards. Note that whilst older SATA devices (SATA-1 or 2) can be used on newer (e.g. SATA-3) motherboards (-albeit slowing things down), the reverse is not true: if you have a SATA-2 motherboard, you cannot connect a SATA-3 device to it

As a general rule, it is best to go for SATA drives (-if you have a choice) to allow future upgrade options.


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