The reliability of modern computer systems is rather high, but still we may see that failures occur there from time to time. It is caused by the malfunction of hardware, bugs in software, computer viruses as well as the errors of users, system administrators and technical personnel. Analyzing all causes that lead to loss of data we can say that all of the failures occur with equal probability that are really important to know for data recovery process.
Disappearance of data can be caused by failure of different devises as hard disk drives and controllers, cables, main memory or CPU of a computer. Sudden disconnection of power supply or the absence of uninterrupted power supply can be also one of data loss problems. The consequences will be more or less severe depending on what was happening in you computer at the time of failure.
In most cases we faced the occasions of data loss during failover of disk controllers. In that situation the controller was making a recording operation that finished with failure. As a result, disk system areas become destroyed that caused the loss of entire data or its part. Note that disk controllers of modern file servers protocol failures of hardware and allow you to make a diagnosis. This gives a possibility to detect dangerous symptoms before they cause a denial.
The easiest method to increase the reliability of data storage is to connect two hard disks to one controller and create a mirror image by means of OS. One disk plays the main role, while the other one duplicates all the information recorded on the main disk. In case of main disk failure its functions automatically transfer to the mirroring disk. As a result, the system works without an emergency stop. Unfortunately, mirror disks will not help if a controller or software fails. In fact, this technology can help you ensure from such trouble as failure of the hard disk of the mirroring pair. The reliability will increase if each of the mirroring disks would be connected to its own controller. In this case the system will continue working with the failure of a disk controller as well. It is one more way for you to avoid undelete tools usage.
A few words must be said about failures occurring within disk devices. In addition to mechanical damage caused by negligent handling of disks, there are failures of electronic circuits located outside or inside the hermetic shell of a disk. Failures of these electronic circuits can cause loss of data. You may find many examples when it was possible to recover all data recording it to another disk with the help of electronic substitution.
We looked through some reasons of data loss that can happen with any computer. You should be always thorough and provide all measures to protect your computer form disk recovery procedures.