Data Recovery involves the process of restoring data that has become unavailable because it has been damaged, corrupted or simply become inaccessible.
Lost files can range anywhere from documents, pictures, emails and databases that have become unavailable due to mechanical failures, deletions, viruses, water damage, mishandling and others.
In a classic example, the cost to professionally recover data can cost thousands of dollars, but today with the advancement of technology and more and more recovery strategies in place, the process of data recovery has become a bit more comfortable.
Data recovery aims at salvaging data from damaged, failed, corrupted, or inaccessible secondary storage media when it cannot be accessed normally. Because data can be lost because of several reasons, the means of recovering data are also several. Your data device sometimes illustrates symptoms of lost data, many of which are mentioned below:
Sounds heard from device
Hard disk drive not spinning up
Damaged electronics controller card
Detection of smoke
Corrupt device firmware
Hard disk drive components failure
Fire or water damage
Media surface contamination / damage
Inaccessible drives / partitions
Virus attack has corrupted the file system
Accidentally deleted files / directories
Accidental reformatting of partitions
Missing or deleted partitions
Computer won't boot
RAID controller failure
RAID configuration lost
Accidental reconfiguration and initialization of RAID array
Multiple drives failure of a RAID array
RAID partition missing
Water damaged tapes
Tape backup failures
If your data is important, seeking professional help is a must, regardless of the condition of the data storage media.
Physical damage to storage media like CD-ROMs can happen when the metallic substrate or dye layer is scratched off. Hard disks can suffer several mechanical failures including head crashes and failed motors. Most physical damage cannot be repaired by end users. There, Data Recovery Service is essential to get the data back. For example, opening a hard disk can cause other unnecessary consequences like the entry of airborne dust to settle on the platter and become caught between the platter and the read/write head, causing new head crashes that further damage the platter and thus compromise the recovery process.
To put it simply, the process of professionally restoring data from a storage device like this requires more than just the know-how. End users generally do not have the hardware or technical expertise required to make these repairs. Consequently, data recovery companies are often employed to salvage important data. These firms often use "Class 100" / ISO-5 cleanroom facilities to protect the media while repairs are being made. Any data recovery firm without a pass certificate of ISO-5 cleanroom or better will not be accepted by hard drive manufacturers for warranty purposes.
Some symptoms include:
Hard disk doesn't spin up
Drive catches a fire
Inaccessible hard drive
Corrupted file system
PC doesn't boot up
Deleted or lost partitions
Clicking noise from drive
Files that have been lost as a result of severe electronic failure would require physical recovery procedures. Some of these include removing a damaged PCB (printed circuit board) and replacing it with a matching PCB from a healthy drive and performing a live PCB swap (in which the System Area of the HDD is damaged on the target drive which is then instead read from the donor drive.
Today, professional experts have developed many powerful data recovery programs to scan the whole drive to check where the problem really lies.
Disk imaging is the process of using the extracted raw image to reconstruct usable data. Open source tools such as DCFLdd or DOS tools such as HDClone can usually recover data from all sectors, except the physically-damaged sectors. DC3dd, a tool that has superseded DCFLdd resolve this issue by accessing the hardware directly.
Another tool that can correctly image damaged media is ILook IXImager, which is only available to government and Law Enforcement agencies. Typically, Hard Disk Drive data recovery imaging can (a) communicate with the hard drive by bypassing the BIOS and operating system which are very limited in their abilities to deal with drives that have "bad sectors" or take a long time to read. (b) read data from “bad sectors” rather than skipping them. (c) handle issues caused by unstable drives such as resetting/repowering the drive when it stops responding or skipping sectors that take too long to read, and (d) pre-configure drives by disabling certain features, such a SMART and G-List re-mapping, to minimize imaging time and the possibility of further drive degradation.
Logical damage constitutes the damage of a file system. Common reasons could be virus activity or human error that might include unintentional formatting or deletion of hard disk, software errors, and lost partitions. All these can ultimately cause a total loss of data or full system failure.
Two common techniques used to recover data from logical damage are Consistency Checking and Data Carving. While most logical damage can be either repaired or worked around using these two techniques, data recovery software can never guarantee that no data loss will occur.
Consistency checking involves scanning the logical structure of the disk and checking to make sure that it is consistent with its specification. This strategy suffers from two major problems. First, if the file system is sufficiently damaged, the consistency check can fail completely.
Data Carving is a data recovery technique that allows for data with no file system allocation information to be extracted by identifying sectors and clusters belonging to the file. Data carving usually searches through raw sectors looking for specific desired file signatures.
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Tammy Harris is a Computer Technician who works on Data Recovery Service remotely. And would like to give his tips how to recover lost or deleted data.
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