Delete & Recover Data (Part 1)

10/9/2012 3:39:22 AM

The most valuable part of your PC is not the hardware itself, but I the wealth of personal and often irreplaceable data stored on its hard drive. From family photos and video, through emails and household accounts to reports and presentations for work, their loss could involve time-consuming recovery at best, or be gut-wrenching at worst.

Description: Delete & Recover Data

Delete & Recover Data

Yet it's so easy to make a mistake. All it takes is one press of the Delete key and your valuable data is consigned to oblivion. And it gets worse: spinning at 7,200rpm for eight or more hours per day, it’s a minor miracle that hard disks are so reliable - but nothing is immune from failure. If your disk suffers a crash it could take with it all your data. Even something as apparently innocuous as a power failure could wreak havoc if Windows was writing to your disk at the time.

Before you get too depressed at the prospect of impending doom, we have good news. Windows may not be able to see a file that you accidentally deleted or was the victim of a disk failure, but it's possible that the data could still be there. And if it is still present, there are several ways in which you can retrieve it.

Of course, there’s a flip side to this. Sometimes you really do want to delete a file, so it's worrying that apparently deleted files can be recovered with ease. If you swap PCs with a work colleague or sell your laptop, for example, you need to be sure that the new user won’t be able to access the personal data you've previously stored on its hard disk.

Even dumping an ancient computer at the local tip or recycling centre could be risky. By using some of the techniques we discuss in the first part of this feature, anyone could gain access to your passwords, financial details and home address - even if you think such details have been erased.

Again, with our help, we’ll show you in the second half of this feature how to ensure that sensitive data is impossible to recover. You could guarantee this by subjecting the hard disk to some serious abuse, but we’ll also show you how to securely delete your data in a slightly less spectacular but more environmentally responsible fashion.

Recovering Data

Chances are you're well aware of Windows' Recycle Bin; it’s the first place to look if you've accidentally deleted a file. When you select a file and press the Delete key (or right-click and choose the Delete option from the context menu), Windows makes no attempt to actually delete it.

Description: Recovering Data

Recovering Data

Instead, it moves it to a special folder called the Recycle Bin, which has its own icon on the desktop. Restoring a file from the Recycle Bin is a matter of double-clicking the desktop icon to display its contents, then right-clicking a file and selecting Restore.

Don't rely on the Recycle Bin as a safety net, though: it has a size limit and, once exceeded, older files will in fact be deleted. The default size is more than adequate for most people, so there's a very good chance that any files you want to restore will still be present in the Recycle Bin. To check or alter the capacity, right-click the Recycle Bin and choose Properties

If you’re in the habit of deleting files by holding down Shift as you press Del or select Del from the context menu, files are deleted rather than moved to the Recycle Bin. Similarly, if you choose to empty the Recycle Bin by right-clicking it and selecting 'Empty Recycle Bin', the files will be deleted and no longer available to Windows.

When gone isn't for good

The term ’delete’ is something of a misnomer here, though. Details differ depending on the file system in use (hard disks often use a different format to flash drives, for example) but, in essence, all that happens when Windows deletes a file from the hard disk is the Master File Table (a system file Windows uses to keep track of the physical area of the disk occupied by each file) is modified. The areas of the disk occupied by the deleted file are marked as available for re-use.

It should come as no surprise, therefore, that a software utility capable of delving into the Master File Table should be able to restore the ’deleted' files. Several programs can do this: turn the page for a step-by-step guide to using the free DiskDigger utility.

Description: Easily Recover Deleted Files From Hard Drive, Flash Drives And Memory Cards With DiskDigger

Easily Recover Deleted Files From Hard Drive, Flash Drives And Memory Cards With DiskDigger

However, file recovery isn’t always plain sailing, so it pays to understand its limitations. The most important thing to note is that time is of the essence. If the areas of the disk previously occupied by the file are marked as available for re-use, Windows will eventually overwrite them; when that happens, your data is gone for good.

The sooner you realise you've accidentally deleted a file, the better your chances of recovering it. Don't save anything to the disk until after you've tried to recover your data. Given that installing a file-recovery utility involves writing to the hard disk, it’s worth installing one now as a precaution. Failing this, look for software that you can run directly from a USB flash drive, so that downloading and installing it doesn't inadvertently overwrite the portions of the hard disk that contain your missing data. Even browsing the web to find an undelete utility causes files to be written to your disk so, if possible, use a different PC.

Best practice

Undelete utilities are able to work reliably only with sequential files. If your disk is reasonably full, Windows will split new files across spare blocks around the disk. Such files are very difficult to recover.

Different types of drive use different file systems, and undelete utilities work only with particular types of file system. Hard disks in Windows PCs use the NTFS file system, but USB flash drives usually use some variant of FAT (FAT16, FAT32 or exFAT). Be sure to select software with the necessary support for all your media.

Another drawback with most undelete utilities is that they won’t work with networked storage, such as NAS drives. The disks in a NAS drive are under the control of the drive's own operating system (usually a Linux variant), so software running under Windows isn't typically able to attempt a recovery. If you’ve accidentally deleted a file then it might be in the NAS drive's own recycle bin (if enabled), in which case you should be able to recover it; check the documentation for your model. If it’s not here, you have only two options.

Description: a NAS drive attached to wireless route

a NAS drive attached to wireless route

Provided that you don't mind getting to grips with the insides of the NAS drive and your PC, it might be possible to remove the disks from the NAS and attach them directly to your PC. A Windows recovery utility may then be able to recover your files, but only if the drive uses the same file system.

Note that NAS drives that use a Raid array may split your data across more than one disk. Some recovery software supports Raid arrays, so it’s worth bearing this in mind when making your selection.

If you don't fancy dismantling your NAS drive, the other option is to send it to a professional data-recovery company. We'll look at these services overleaf.

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