HardDisk

The hard disk (or hard drive) is the permanent storage area of your computer. It stores information whether the computer is on or off. A hard drive is a mass storage device found in all PCs (with some exclusions) that is used to store permanent data such as the operating system, programs and user files.

The data on hard drives can be erased and/or overwritten, the hard drive is classed as a non-volatile storage device which means it doesn't require a constant power supply in order to retain the information stored on it (unlike RAM).

Inside every hard drive are small round disk-like objects made of either an aluminum/alloy or a glass/ceramic composite, these are called platters, each platter is coated with a special magnetic coating enabling them to store data magnetically. Hovering above these platters are read/write heads that transfer data to and from the platters.

Hard drives come with many different storage capacities, hard drive capacity is measured in bytes, with common capacities being stated in MB (Megabytes) and GB (Gigabytes).

Hard Drive RPM Speeds

You will often see hard drives advertised as being capable of a certain RPM (Revolutions Per Minute), this figure (as the name suggests) refers to how many times the spindle makes a complete 360? turn in any single minute.

RPM values range from about 5,400RPM to 12,000RPM and above.

How to Choose a Hard Drive

When you are choosi ng one Hard Drive you have to consider:

ATA and SCSI

In the hard drive world, there are two data access standards, ATA and SCSI (pronounced 'Scar-Zee'). Most of normal hard drives we're used to rely on the PATA standard. Some newer hard drives use the SATA standard.

SATA allows transfer speeds of up to 150 MBs while PATA gives up to 133 MBs. However, to use SATA, you'll need a Serial ATA controller, a SATA drive and a SATA power cable. The speed difference between PATA and SATA is also not significant unless you have a high-end SATA drive.

The SCSI standard is a very fast hard drive standard used for professional computer systems which demand extremely fast data access. SCSI drives provide an access time of about 9.5ms - which I feel is really not needed for average home use.

 

Disk Space vs. Price

An important factor to consider is the disk space versus price ratio. When you look at the 30 GB, 40 GB and 80 GBPATA hard drives, you'll find they are very close in price. For the average home user, however, 40 GB to 80 GB of disk space is plenty.

Drive Speed

If data access speed is important to you, you can go for faster SATA drives or SCSI drives. But remember that these drives come at a price premium and may not be necessary for average home use.

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