Hard Drives explained

Hard drives are the main storage component of your computer, which are sometimes referred to as a hard disk drive and abbreviated as HD or HDD. The first hard drive was announced back in 1956, it comprised fifty 24-inch diameter disks (platters) and could store 3.75 megabytes of data. The hard drive’s cabinet was 60 inches long, 68 inches high and 29 inches wide.

First IBM hard drive, 350 RAMAC
First IBM hard drive, 350 RAMAC

Today’s hard drives come in two sizes, 3.5 inch and 2.5 inch. The size refers to the diameter of the platters where the data is written. Desktop computers tend to have 3.5 inch hard drives and laptops have 2.5 inch hard drives. Both sizes can be found in external hard drive enclosures.

3.5" and 2.5" hard drives
3.5″ and 2.5″ hard drives

Hard drives also come with two different connection types, IDE (PATA) or SATA. SATA cables have much faster data transfer speeds than IDE which allows programmes to load faster. The cables are smaller in size allowing increased air-flow inside the computer case and the length of the SATA cable can be up to 1 meter in length allowing more flexibility on where a hard drive can be mounted, whilst the IDE cable has a maximum length of 18 inches.

SATA and IDE connections
SATA and IDE connections

Your hard drive has a controller board which communicates between the computer and the hard drive, it controls the motor, tells the head to read and write data and exchanges data. At least one platter is attached to a spindle which spins at 5400/7200/10000 rpms. Each platter has a read/write head on a fixed arm which is controlled by an actuator (motor). Data is magnetically stored on the platter and the spindle is spun whilst the read/write heads are moved into place by the motor to where the data is stored.

With a number of components that can go wrong it is important that you keep regular backups of any pictures, music, files etc.

A lot of computer manufacturers ‘partition’ the hard drive into two separate ‘drives’, normally calling the second partition DATA. In most instances I have seen, this section of the drive is left empty whilst the other half of the drive is steadily filled up until the computer slows down quite considerably. This normally happens because when a computer is set up, the main folders for documents, pictures etc are on the C drive and people will save the files to these folders.

People also think that storing backups on the ‘DATA’ drive is a safe option, but if the hard drive fails then this will mean that all partitions on the drive will have failed. Whilst data recovery options may be available to rescue data, they are generally expensive and not 100% guaranteed.

The best option is to have a second external hard drive which your important files can be written to and stored away from your main computer. Then, if anything happens – failure, theft, fire – at least your files will be on a separate medium and can be restored to a new hard drive if necessary.

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