Doing the Hard Yards

August 1st, 2003 APC, Tech, Tech Features

We can be forgiven for thinking computers are particularly tough machines. We shove them under desks, accidentally kick them, pile peripherals unceremoniously all over them, and they say you can tell someone who’s never opened a computer before by how careful they are — a technician in his/her natural environment maintains all the tenderness of a lumberjack.

Don’t be fooled. A hard drive can go wrong for a whole lot of reasons, and when it does it’s usually cause for the most panic as you’ve potentially lost the only thing on your computer that can’t be replaced — your data.

And don’t wait for a lightning strike or house fire, either. Like a car chassis, the tiniest knock of just the right (or wrong) angle and strength can cause a major failure; anything from a BIOS breakdown to boot file corruption to a head crash.

Of course, you should already be doing something about hard drive failure; pre-empt it and prepare for the worst. It’s a tired old mantra, but perform a regular backup.

A hard drive failure doesn’t mean all is lost. As we love telling the computer illiterate, deleting data doesn’t mean it’s gone. The same principle applies in data recovery — theoretically you can retrieve data regardless of the fault (or error) short of physical destruction of the disk. The catch? It’ll cost you.

Your local computer shop might tell you the situation’s hopeless, but even if you had to go to the NSA, a method exists somewhere that’s worked for a worse case than yours. It’s said data can be recovered from a disk reduced to a metallic blob by fire, with the right expertise and money.

It’s also a race to a non-existent finish line. As computer data becomes more instrumental to society, security demands increase — therefore so do the tools needed to circumvent them. It’s safe to assume that no data is ever truly gone — not even if you smash your disk platters with a hammer.

A Healthy Disk

If the disk itself is undamaged, the problem might lie with other hardware outside the platters and head assembly. Your BIOS might not recognise a new component or just break down through wear and tear. You might have damaged connections inside the drive housing.

Or it could be software based, like a virus that corrupts startup files. If you get an error message (or nothing at all) during bootup, an average commercial operating system can be booted from the CD, and you may have created your own emergency boot disk. Then at least you can run diagnostic software like Systemworks (PC/Mac), or Scandisk (PC) to isolate and fix the fault.

If you have the means, a manual (but workable) solution is to install your OS on a server or second computer, boot up from there and access the damaged drive in the same way your desktop OS accesses removable media. You can literally drag and drop the files you need to recover off the damaged disk, reinstall a clean OS onto it and change it back to your boot drive.

Otherwise, if the problem seems to affect certain functions or files and you feel you may have a virus, a virus checker with updated definitions should do the work for you, directing you to a patch or update.

If you’re confident of isolating the problem and correcting it, you can’t hurt too much as long as your data is backed up. The worst than can happen is you’ll just have reformat the disk and reinstall everything.

If you’re unsure, get advice from a technician. Any expert worth their salt will be familiar with your problem from your description on the phone and walking you through the solution might take no time at all.

Disk Damage

The more forbidding hard disk problem is damage to the disk itself, and the causes are as individual as your desktop picture.

If your hard drive is damaged, the first trick a professional technician has to do is get it spinning. The physical structure of the drive itself can be damaged while the data on it is almost completely intact. It might be warped, partly melted, or otherwise out of shape. Machines exist (or can be engineered) that can get a disk spinning at the right rate for a read/write head in almost any example you can think of.

Once it’s made to spin as if it’s inside a PC, special (or even everyday) heads can be employed to read the data. Obviously the disk itself will be unusable in future, but at least you’ll get your data back and the rest is for the insurance company to worry about.

If the data is unreadable because of a structural problem like a scratch inflicting bad sectors, it’s more serious. It’s not impossible to get around though; one data recovery service in Sydney uses a technique that reads a bad sector up to 1000 times. Out of 3 or 4 half-decent reads that pick up enough bits, the sector can be recreated with astonishing accuracy somewhere else for reinsertion into the readable data.

The Perils of Overwriting

Just like there are two basic kinds of data problem, there are two kinds of fixes, and the distinction is important to understand.

If you use your boot disk to perform any function, you’re modifying data — writing new data to the disk. A hard disk isn’t a filing cabinet with neatly categorised documents. A single file can be spread over several platters — it’s the job of the read/write heads to access and reconstruct it.

So the very act of writing data to the disk will be overwriting other data, and that may be data you’re trying to recover. Keep that in mind when you use a software-based method directly from your boot drive. Many, from free OS utilities to dedicated software like Norton Systemworks do a good job, but they potentially bury your lost data deeper.

Mirror Image

A safer method is to recreate the disk. Some data recovery services sound impressive with big words and technical jargon, but they might simply be running off-the-shelf software tools over your disk. Sure they might sound better than the ones you have access to, but if they’re making your data even more inaccessible, they’re no better than a dodgy freeware download.

The safer method is to take a disk image. Special equipment can be used to completely reconstruct the contents of a damaged disk (using the multiple read method mentioned above to get the full picture if necessary) one bit at a time. It literally builds a mirror image of data on a new disk using every individual 1 and 0.

Then you’re free to make a few copies to try different methods on each. Even if you do use software scans that further write over one of your copies and the recovery doesn’t work, you can start from scratch on another and your original drive remains unmolested.

Tips

‘ Some services offer a free initial inspection. Sounds great, but you get what you pay for. You’ll probably end up paying for those ‘free’ hours somewhere along the line anyway.

‘ An up-front inspection charge should entitle you to a detailed report of what can be done and how much it’ll cost. It also gives you the option of only paying for what you want retrieved and not an entire disk.

‘ There’s no ‘standard’ rate for data recovery — it depends on the extent of the problem and the methods needed, and good methods aren’t cheap. Work out how much your data is worth to you — even if it’s not commercial, it might be priceless.

‘ A decent data recovery service shouldn’t object to you calling for advice. At the very least it will give them foreknowledge about your case if you decide to use them, and it’s a good test to see if they know what they’re talking about (or are just subcontracting your recovery to someone else).

‘ Even if you can get the best possible software, it’s useless in inexperienced hands. Don’t assume you’re paying someone to just click a button but don’t be afraid to ask what they do.

‘ Each case is different. Some software promises generic results (there’s even one that promises to retrieve your data over the Internet!) but be wary of one-size-fits-all solutions.

Removable Media

With the exception of CDs and DVDs, the majority of removable storage media for the personal computer works the same way as your hard disk — a hard disk is just a more protective setup because it contains the files that drive the computer. Where hard and floppy disks use magnetism, CDs use light.

Whether it’s a floppy, Jaz or Zip disks (even a dinosaur like the Syquest), all magnetic computer disks comprise a housing containing a round piece of plastic, glass or metal. A mechanism inside the driver spins it, and a read/write head (or laser in the case of a CD) scans the surface, reading the blips that signal binary code.

Master and the Slave

Recovering lost data from a removable disk is (in theory) easier because you’re not writing to the disk you’re trying to retrieve from. Whereas self-help fixes on hard disks involve booting from another drive, your standalone PC already treats removable disks that way, so you can be reasonably sure no new data is being written to the disk you’re trying to retrieve from.

The reason that’s important is because the best recovery software in the world won’t do you any good if installing it overwrites files you’re trying to get back.

But a strong word of warning; no method is 100% safe. Different recovery software works in different ways, and while some perform scans that don’t interfere with the data on the target disk, others write small index files or markers on the disk they’re searching. Overwriting or further damaging file headers you’re hoping to get back is the last thing you want. Make sure you know how your software works — get advice from a professional lab before you start.

The Diagnosis

Before you do anything, make sure the problem is really the disk. Frequent read errors make it seem like you’ve got faulty disks, but removable drives suffer read failures for all sort of reasons (making your system think the disks are the problem). You might have to update your BIOS or drivers, or replace the whole drive — they’re not as robust as hard disks and get a lot more exposure to the environment.

Get a New Image

If the disk is definitely at fault, the first step in a 100% safe recovery is to write a disk image or copy. Virtually every Windows and Mac OS over the last five years includes a disk imaging utility (called Disk Copy in both current platforms), so you’re free to try as many recovery methods on as many copies as you like — right on your desktop.

You might get lucky, but in theory, you’ll just be making copies of the same bad sectors. If commercial restore utilities don’t help, it’s then time to consider a data recovery service.

The Professionals

Using a system that performs multiple reads on bad sectors, experienced recovery labs can more or less completely recreate your data — even data from bad disk sectors. By reading every bit on every sector on the disk, they can ‘regenerate’ it to a virtual disk with full visibility of the data (or at last a portion of it).

The Great Disk Drive in the Sky

Hard drives are a lot easier to look after — they stay snugly in a CPU on your desk (or at worst, take a little buffeting in your carry-on luggage). Removable disks like floppies or CDs get dropped down the back of the lounge, chewed by the dog, melted on the back seat of the car or steadily demagnetised in the shadow of your monitor.

Like any data drive, nothing can be read from it before getting it to behave like it does inside your PC. Making it spin at the right speed isn’t something most of us have within our reach if it’s been warped, burned, melted or even broken in several pieces, but a good data recovery lab will have the equipment to do just that, and the cost depends on the extent of the damage.


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