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Hard Disk Data Recovery


What is Data Recovery?

Unfortunately for us all there comes a time when we turn our PC on and it simply doesnt start up. Or after a few hours of operation the computer freezes and a press of the reset button results in a machine that doesnt start up properly or even worse, asks you to insert bootable media and reports that there is no hard drive present. Inevitably these problems occur when we have no recent backup of our data or immediately after spending hours entering data into a critical database or program.

Data recovery is the act of salvaging whatever useful files that can be retrieved from a hard disk, RAID array, CD/DVD, USB or tape drive that has failed in some way and cannot be accessed in the normal fashion.

In this section of DIY Computers we will examine the different ways that a hard disk or other storage device can fail and the techniques used to recover lost data in each particular instance. This section of the site comes with a dire warning however, some of the data recovery techniques we will discuss require a clean room and a high level of expertise that make them unsuitable for beginners or even professionals to attempt. Particularly when considering repairing electronic or mechanical failures you must place a value on the data that you are trying to recover. Are you attempting to recover your companies customer database or last seven years of accounting records? If the data is absolutely critical do not attempt to recover it yourself, it may be lost forever in the process. Turn the computer off and leave it switched off and out of harms way. Contact a professional such as a computer technician or a specialised data recovery company, come to terms with the fact that they will charge accordingly and have them recover your data for you. Theres no point in saving $1500 on a professional data recovery service if the data you have lost is worth millions.

Types of Data Loss and Data Recovery Methods

It goes without saying that the best data recovery method is to back up data regularly and incrementally and not need to recover it at all. This strategy does not always reflect the real world but if your backups are less than 24 hours old they are far more useful than the ones you did before the holidays last year. Adopt a backup strategy in line with the nature of your data. If its absolutely critical data then backups performed once a day after hours is a great starting point.

Assuming that its too late to fall back to a backup and you have already lost data in some fashion then the success of the recovery of your data may rest on what you do next. If your files have been lost or are inaccessible because of an electronic or mechanical failure of your storage media in particular then every second that the drive or device has power may be damaging more of your data. Assess the situation as quickly as possible, making note of the devices behaviour and then switch it off and consider the situation carefully. Your loss of data will fall into one of the following three categories, each of which we shall examine on their own seperate pages.

Loss of files or data after an operating system failure is the most common instance where data recovery is necessary and fortunately the most easiest to resolve with a high success rate. The hard drive or storage media is in good health however the host operating system, whether it be Windows, Linux, Mac OS or what not, is unable to boot up or start in a normal fashion thus making your data inaccessible. If this sounds like your problem please read Recovering Files After an Operating System Failure.

Loss of files or data after a hard disk or file system failure can be more difficult to resolve. Symptoms include the computers BIOS reporting no hard disk drive present, the hard drive being detected but not readable or the operating system failing to start with error messages that indicate bad media. Unfortunately this type of failure may mean that not all of your data may be recoverable, if any at all. If this sounds like your problem please read Recovering Files After a Hard Disk or File System Failure.

Recovering files or data that has been deleted is the final instance where data may have been lost. On some operating systems it is quite possible to recover deleted files. Your level of success will depend on whether other files have been written to the same data blocks that the files were deleted from. Please read Recovering Files that have been Deleted.