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Last Updated: Tuesday, 22 May 2007, 08:00 GMT 09:00 UK
Testing the limits of hard disk recovery
By Darren Waters
Technology editor, BBC News website

Hard disk drive
Hard drives have become the medium of choice for consumer storage
As our digital appetites increase, so does our need to store our data.

But as we move into the terabyte age with trillions of bytes of storage available for a few hundred pounds, can we rely on hard disk drives to safeguard precious information? And what happens when they do fail or are damaged?

When I had my first computer in 1983 it had 32KB of memory and it was not until 1988 that I had my first hard drive - which had 40MB of storage.

Almost 20 years later and my main desktop can store 160GB of data while my laptop has 120GB and I have a pocket drive with 40GB more capacity.

My back-up routine is poor - I have my music and photos archived on several DVDs but it has been months since I last backed them up.

If the hard drive in my main computer were to fail, I would lose thousands of photographs and hundreds of songs. Every hard drive is a crash waiting to happen and so it is clear I should invest in a back-up storage system.

With 500GB of external hard disk storage available for as little as 89 online and the first terabyte single hard drive released at the start of the year, there is no excuse not to back up.

Hard disk drive

A recent report from Google engineers suggested that there is no link between heavy use and hard drive failure.

Hard drives less than three years old that are used a lot are less likely to fail than similarly aged hard drives that are used infrequently, according to the report.

However, a Carnegie Mellon University report recently suggested that the failure rate of hard drives used in the business sector was a lot higher than manufacturers' claims.

So what happens if your hard drive fails or is damaged in an accident? To test durability we put a basic 40GB external hard drive through a series of vigorous challenges.

On it we had some photographs and documents and challenged data recovery firm Kroll Ontrack to retrieve our data.

We dropped the drive out of a second storey-window, immersed it in a pond, drove over it and hit it with a hammer.

Was the firm able to retrieve our information?

Rob Winter, chief technology officer at Ontrack, said: "It was very badly damaged and we couldn't recover the data.

Open up the picture to see what happened to our hard drive.

"The fundamental reason it wasn't recoverable was that many laptop hard drives have platters made of glass and in this case they shattered. When that happens it is impossible to get the data back.

"Usually laptop hard drives are glass while workstation platters are metal. If the platters had been metal we might have been able to get something back. It all depends on the dents and kinks in the platter."

We went to extreme lengths to damage our drive - too extreme as it turned out. But what are the typical types of damage seen at the firm?

Phil Bridge, managing director at Ontrack, said: "Dropped laptops and spill damage is common. We also see a lot of drives where data has been deleted accidentally.

"In those cases we can typically retrieve 100% of the data."

Mr Winter said: "The first thing we do is make an exact image of the media on the drive. The reason for that is that the drives are often failing or have failed and the best way of preserving the best image we can get is to process the hard drive on to an exact copy.

Extreme experiments to destroy a hard drive

"If we can't create the image because the hard drive has failed, it would then go to our clean room and they would investigate the problem.

"In most case that involves taking the lid off, looking at the internals. Essentially the task is to fix the drive sufficiently to read the data off the platters."

"We then generate a list of all the files we can get back and send it to a customer who can then choose what they want back."

If you do spill water or a liquid on a hard drive, the temptation is to dry it out on a radiator.

Phil Bridge said: "Don't do this. The hard drive could be damaged more by oxidisation through drying out that from getting wet. We advise you to bag it up and get it to us as soon as possible."

As part of a media visit to Ontrack, the company was given a second hard drive that had not been readable in years and, as part of a test, had been immersed in hot tea.

Mr Winter said: "We thought it was glue on the disk. We were having no luck but the last technique we tried was to remove the platters from the hard drive. Right underneath the bottom platter there was the tea and sugar mix

"We cleaned the platter and then reassembled the hard drive and recovered the data."

Data recovery firms are also starting to see customers asking for help with USB memory sticks.

Hard drive
Kroll Ontrack will make a copy of any data on a drive

One Ontrack client asked for help after their dog had chewed the memory stick.

"People are still using hard drives to store important information," said Mr Winter.

He said solid state drives were more durable but the types of failure were different.

"Failures from electrical surges are more common," he said.

Data recovery can be an expensive business; work done in the lab to recover data can cost hundreds of pounds.

As with any data storage, it is better to be safe but with modern recovery techniques your important files can be retrieved - at a price.

But if you were to accidentally drop your hard drive, better to avoid also dunking it in water, driving over it and bashing it with a hammer.

Hard disk test 'surprises' Google
19 Feb 07 |  Technology
Hard drives for 'terabyte lives'
11 Jun 05 |  Technology
Google helps terabyte data swaps
07 Mar 07 |  Technology

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