It is much more common for logical damage to occur than physical damage. Most of the time, logical damage comes about as the result of a power outage, which will prevent the structures of the file system from being written to the desired storage media. As a result, the file system remains inconsistent. If your system is behaving in a strange fashion or crashes, you might lose some pertinent data that will have to be recovered. Thankfully, it is much easier to do this when it is a case of logical damage, rather than physical damage.
In fact, most operating systems come equipped with their own repair tools. These tools typically employ one of two techniques.
The first is consistency checking. This process involves the scanning of the disk’s logical structure. After it is scanned, it is then checked to ensure that the disk is consistent with its specification.
The second technique is to effectively rebuild the entire file system from scratch by utilizing any hints that undamaged file structures might have left behind.
These two techniques guarantee that most data will be recovered – ninety percent of the time. But that does not mean that data loss never occurs as a result of logical damage. Sometimes, in the FAT file system for example, if two files are cross linked, then data loss for one of those files will most likely occur.
It occasionally happens that logical damage is mistaken as physical damage. For example, on those occasions when someone’s hard drive begins clicking, a lot of users will assume that it comes as the result of physical damage, when in actuality, it could be due to logical damage. In these instances, the firmware on the system’s controller card simply need to be rebuilt. Once the firmware is restored, the data will become accessible once again.
By using journaling file systems like XFS, you can reduce the chances that logical damage will occur to your operating system. These systems ensure that the only data that will be lost in the event of a power outage will be whatever was on the drive’s cache at the time that the outage occurred.