January 15, 2014

Principles of Hard Disk Data/File Storage and Format

Why we still could restore or retrieve deleted file or data in computer, including file and data you delete or format accidently or because of system partition damage, cloning reduction system or disk data unable to read and write? Please follow and read the principles of hard disk data and file storage, hard disk format to get answers.

1. How to read file in hard disk?

Windows operational system reads file information from directory, including file name, file name extension, file size, modification date and cluster number of first cluster of file in data zone. Now we suppose the first cluster is 0023. Windows will read data from cluster 0023. And find 0023 unit in FAT. If it reads the ending mark, it means the file has been read completely. If not, save the next cluster number of data until Windows finds file ending mark.

2. How to write file in hard disk?

When we prepare to save files in computer, Windows operational system will find an empty zone in DIR to write down file name, file size and creation date etc information. And find empty zone to save file in Data zone. At the same time, write the first cluster of Data zone into DIR zone. Other operations are similar to the file read in hard disk.

3. How to delete file?

When we are going to delete file or data in computer, Win 9X system just change the first character of file in directory and instead it of E5, not delete it from computer completely.

4. How to format hard disk?

Hard disk only could be used after disk partition, disk format and Windows operational system installation are finished. The complete disk data includes five parts, MBR, DBR, FAT, DIR and DATA. There is only one MBR, but other parts could increase following the increasing of partition.
Hard disk format program only rewrites FAT table and modify MBR and OBR when we format disk. Many data on DATA zone have not been changed. This is the reason why hard disk could be recovered.

From the principles of disk format and data deletion, we know data could be recovered if we find the starting location of file. But please pay attention to that you have not covered this file before data recovery.

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