What Is a Hard Disk Drive?

Your Hard Disk or sometimes called a Hard Drive, is the main storage space inside your PC. It is a permanent storage component unlike the RAM (Random Access Memory). It is possible for your computer to function without a hard disk, however it would be basically useless to you as you would not be able to use an Operating system or have any programs to use. Unless you had another form of mass storage device such as an SSD (Solid State Drive).

Hard disks use circular hard platters to store data on. They are in pristine condition with a mirror like finish to them. These platters are locked away inside a steel casing as unclean air can easily ruin a hard disk. This is why you should never remove the casing from the hard disk, it is very unlikely you will be able to put it back together as a working component. Even a small amount of dust can render a hard disk platter useless.Above you can see a labeled diagram of a hard disk. The model is a SCSI (Small Computer Scientific Interface) You can see the hard platters on top of each other with a set of arms which hold the read/write head. The speed of the arm is truly amazing as well as the accuracy of the head which can read and write to perfection on a platter which is rotating around 7200RPM. The hard disk looks a very simple idea and probably is, however a lot goes on before the simple writing to the disk its self. We will explain a little more later in the article.

How does the hard disk store data?

On each of the platters there is a thin layer of magnetic film. Data storage on hard disks is very similar to that of a cassette tape. Data is stored in many 1's and 0's stored in different directions on the magnetic film by using a very fine oxide. These binary digits are arranged in different ways to represent different characters. When these are read back by the head the data is retrieved and processed. because no physical contact with the platters is made the disk can be re-written time and time again without damage to the disk or its platters.

File Systems

A file system is the way in which your computer stores data on the hard disk. The most common file systems are FAT16 for older computers, FAT32 and NTFS. FAT stands for File Allocation Table. NTFS stands for NT File System. Both have advantages and disadvantages. FAT16 was a very limited file system in the way that it would store data very in-efficiently, every file would take up a minimum of 32Kb in space as this was the minimum cluster size in a FAT16 system. Also it was only capable of using hard disks up to 2Gb in size. FAT32 solved this problem by reducing the cluster size to 4kb which saved a lot of wasted space and also allowed disk sizes up to 2 Terra bytes. NTFS is believed to be a far greater file systems than any of the FAT's. The cluster sizes can be altered to anything as low as 512bytes which means almost no wasted space on the hard disk. The maximum disk size is a unbelievable 256 Terra bytes, which is very big !!!. NTFS also has added security for file loss.