Monday, May 23, 2011

How Data Storaged on Hard Disk

Hard Disk is the main storage space inside our computers. The Hard Disk is a permanent storage component such as RAM. But hardly know how the data is stored on the hard disk. The Hard disks use circular platters to store data. They are a mirror like. When you 'save' data to the hard disk, the disk will follow a logical system. And here we will introduce you the storage method of the hard disk.

The key concept of data storage is that it is linear, logical and systematic in nature. When you 'save' data to the hard disk, the disk will follow a logical system.

The second key concept to remember is that data storage follows a simple rule – data is stored (or 'written') on the first available space, wherever this may be.

Data Storage Example
Imagine that you are saving a 1-Mb Word document on the hard disk. Saving a 1 MB file means the disk will systematically 'fill in' a thousand squares.

After saving the Word document, let us assume that you saved to your hard disk a 3 MB photo. Following the key concepts of data storage, the disk writer head will go through the disk and then look for the first available space – which in our example, happens to be the square following the last kilobyte of the Word document. Thus, the 3 MB photo will be saved at the space next to the Word document.

Afterwards, you go back to your Word document and trim it down, ending up with a file 700 KB in size, which you then save to your hard disk. Given the smaller file size, the 1 MB space requirement was reduced to 700 KB, leaving 300 KB free or (using the analogy above) 300 blank squares immediately after the Word document. There's now available space between the Word Document and the 3 MB photo.

When you save yet another file, say a 2 MB Excel file, the hard disk will follow its rule of saving data on the first available space. Thus, the Excel file will be split into two portions: 300 KB would be written on the 300 KB free space and the rest will be placed in the next available space – after the image file.

The Problem
Data storage, while designed to be logical and systematic, leads to file fragmentation. Imagine adding, deleting files and editing files for days, weeks and months. After a few months, the hard disk will become so fragmented that it would take the disk a lot of time to find fragments of a single file, and the lost documents is nearly can’t be restore only if you take advantage of some data recover software to do so.

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