data_recovery

DATA RECOVERY

Data recovery is the process of salvaging data from damaged, failed, corrupted or inaccessible secondary storage media when it cannot be accessed normally. Often the data being salvaged from storage media such as hard disk drives, storage tapes, CDs/DVDs, RAID and other electronics. Recovery may be required due to physical damage to the storage device or logical damage to the file system. The most common data recovery scenario involves an operating sytem failure in which case the goal is simply to copy all wanted files to another disk. Another scenario involves a hard disk failure, which means the data can not be easily read. In this situation if recovery is needed, then the disk itself has permanetly failed and focus is on salvaging what ever data can be read. A third scenario is accidental deletion. Typically, deleted files are not erased immediately, instead references to them in the data structure are removed and the space they occupy is made available for later overwriting. This means the orignal file is still able to be recovered.

**Recovering after physical damage**: A wide variety of failures can cause physical damage to a storage media. CDs can have their metallic substrate or dye layer scratched off, hard disks can suffer any of several mechanical failures and tapes can simply break. Physical damage always causes some data loss and in many cases the logical structures of the file system are damaged aswell. Any logical damage must be dealt with before file can be salvaged from the failed media. Most physical data can be repaired by the user. For example, //opening a hard disk in a normal environment can allow airborne dust to settle which can cause futher crashes and damage.// Also generally users dont have the hardware or expertise required to make the repairs, so costly data recovery companies are often employed to salvage important data.

﻿**Recovery Techniques:** Recovering data from pyhsically damaged hardware can involve multiple techniques. Some damage can be repaired by replacing parts in the hard disks. This alone may make the disk usable, but there can also be logical damage. A specialised disk-imaging procedure is used to recover every readable bit from the surface. Once this image is acquired and saved on a reliable medium, the image can safety analysed for logical damage and will possible allow for much of the orignal file system to be reconstructed.

In some cases, data on a hard drive can be unreadable due to damage to the file system. In majority of these cases, at least a portion of the data can be recover by repairing the damaged file system using specialised data recovery software. This type of data recovery can be performed by knowledgeable users as it require no special physical equipment. However, more serious cases can still require expert intervention.
 * Corrupt File Systems: **

'Online' or 'Remote' data recovery is yet another method to restore lost or deleted data. It is the same as performing the regular software based recoveries except this type of recovery is performed over the internet. without physically having the drive or computer in possession. The recovery technician sitting somewhere else gains access to the user's computer and completes the recovery job online. Although online data recovery is convenient and useful in many cases, it still carries some points making it less popular then the classic data recovery methods. First of all, it requires a stable broadband Internet connection for it to be performed correctly, which many third world countries still lack. Also it can not be performed in case of physical damage to media and for such cases, the traditional in-lab recovery has to take place.
 * Online Data Recovery: **