Before a disk can store any data, the Operating System (OS) needs to make the drive useful for the file storage system used by the OS. This ensures that the OS can allocate the data onto the drive in a systematic fashion for easy retrieval and access. Disks are, therefore, divided into sectors, and 512 bytes are assigned to each sector. These sectors are then bundled together into clusters or allocation units. All the clusters are of the same size, and contain anywhere between 2 to 16 sectors each.
Thus, on each disk, there is some space assigned for basic disk system operations, and the rest of the space is used to store files and data. There is also an area where a record is maintained of the physical location and properties of the data, and the program files on the disk. Each OS has a different method of storing this information. So when a computer needs a specific file for any operation, it consults this file storage information to find where the file has been stored on the disk, and loads the file into the RAM of the computer.
FAT and NTFS are two methods of saving the file storage record information.
FAT or File Allocation Table is a database system which contains an entry for each cluster on the disk. There are various versions of the FAT system: FAT12, FAT16, and FAT32. The numbers refer to the number of bits used to store the cluster information in the tables. Thus, FAT16 uses 16 bits to store the cluster information in the tables.
NTFS or New Technology File System is used by newer versions of Windows, such as XP and above. In NTFS, all the data is stored in the form of files instead of the fixed structures in the FAT system. There is a MFT, or a Master File Table, which is a relational database where all the storage information can be found.
NTFS and FAT Data Recovery: Important Tips
When a hard drive crashes, it is possible to retrieve the data that was stored on it. Ideally, if the file is undamaged and not encrypted but mistakenly deleted, all one has to do is find it. In the FAT system, one needs to clean the messed up file allocation table. In the NTFS system, the method is a little different. Techniques like cluster remapping and transaction logging are part of the NTFS system, which is geared to automatically perform data recovery operations.
Cluster remapping prevents data loss by automatically transferring the data from the clusters containing bad sectors to good clusters. Transaction logging is another system associated with NTFS, where any operation that creates or modifies a file is logged as a transaction. Thus, either an operation is completed or it isn't, because there are no incomplete transactions. This information is kept in a log file. In data recovery operations on a NTFS disk, one can redo any transaction that is logged into this transaction log.
There are a variety of software which can help you to retrieve data which was lost when the disk crashed. But before you buy such software, it makes sense to see if your disk storage system is FAT or NTFS. Sometimes, the software may be designed for one system and not the other. So, it makes sense to purchase the software designed for data retrieval for the storage system that your computer uses.
But before you venture out to purchase a software, make sure that the problem with your hard disk is in the boot sector (which you can resolve by using the software) and not an electrical failure (where the electrical parts of the disk may have burned, etc.), or a mechanical failure (where the disk or its parts are physically damaged).
It is always a good practice to have a back-up of all the data on your disk. One should always use a firewall and use good virus protection software for the computer to avoid any virus to corrupt the boot sector of the computer's hard disk. Do not use programs such as scandisk, chkdsk, or Norton Disk Doctor as they do not perform data recovery operations. Try to see if a System Restore operation helps in recovering the functionality of your computer. There are also a variety of data recovery services available where trained professionals will do the hard work for you. Usually these services advertise a 'No Data, No Pay' agreement.
Thus, it is possible to recover the data that is stored on your hard disk, even if your hard disk crashes.