There are a number of theories that whatever you do, data from a hard drive can never really be erased. There is always some sort of residual magnetic force that can be interrogated. This really is the stuff of science fiction and even if it is true which is doubtful, it certainly would never be economically viable.

A computer scientist named Peter Gutmann caused much controversy when he published a paper claiming that overwritten data can be recovered using magnetic force microscopy. Even where the binary magnetic returns are overwritten, a sensitive enough instrument would be able to read the subtle changes in magnetic variations. He claimed that to completely eliminate these variations a minimum of thirty five overwrites should be performed so that data cannot be recovered.

Whilst this is all fine in theory, it has never actually been put to the test and remains unproven. Nevertheless, many took his theory as gospel and it has even featured in many high profile computer forensic cases. Peter Gutmann’s theory has become urban legend and clients often refer to this when their data is unrecoverable!

In reality if you want to make sure your data can never be recovered it’s pretty easy. A low level format or secure erasure program will do the job. To be sure though, physically destroy the hard drive afterwards as well. As long as the platters inside are smashed, we guarantee no data recovery company or expert will ever be able to recover the data!

Here at Kroll Ontrack, we’re well aware that data loss can affect anyone. For many of us, it comes in the form of hard disk drive (HDD) failure – an umbrella term for mechanical, electronic and logical defects that render the information stored therein unreadable. There are dozens of possible causes for this type of malfunction, ranging from logical software errors to physical damage and overheating – and, of course, the fact that all storage devices have a finite lifespan.

You might be acquainted with some of the tell-tale signs that a hard drive is on its last legs. Strange noises, for example – if your HDD shifts from whirring and clicking to grinding and thrashing, it’s a safe bet that it’s about to give up the ghost. In addition, slow access times, frequent crashes and abnormal behaviour – such as corrupted data and vanishing files – are reliable indicators of hard drive failure.

Unfortunately, these aren’t what you’d call scientific metrics to detect a HDD malfunction. And while it’s one thing to listen out for odd sounds emanating from your laptop or tower, it’s another to apply the same methodology to a redundant array of independent disks (RAID) environment in a remote data centre.

Seagate has always been the brand leaders in hard drive quality. Sure, they’ve had some issues with firmware bugs in the past, but that is behind them and generally speaking their hard drives are some of the best around. Lately though, they have had some issues with their 3TB series in particular the ST3000DM001, 000 and 002 suffixes.

Take a look at Backblaze’s statistics and the ST3000DM001 has the highest failure rate of all the drives. Ok so Backblaze put hard drives through their paces, but this model has a 28% failure rate. Similarly Apple have a replacement program for any Seagate 3TB drives that fit into this category.

If you have any of the 3TB DM series of hard disk drives, make sure you religiously keep your data backed up. Better still replace the drive. If this is installed in an Apple product check out their replacement program – you may be eligible for a new hard drive!

So what is the problem with these Seagate hard drives? Once again the problems seem to relate to corrupted firmware code stored in the hard drive’s service area. Other issues include the media cache.

Typically we are seeing twice the number of Seagate hard drives for data recovery and most are the DM series. Before you judge though, remember that Seagate are one of the biggest manufacturers and they are still making high quality hard drives. The failure rate is still only proportional with the number of hard drives they produce. So don’t worry unduly unless you have the DM series!

Depending on the type of problem with your hard drive, the user may well only have one attempt at data recovery so make sure you choose the right company! If your hard drive has failed mechanically, a skilled professional is going to rebuild that disk using donor parts. Data recovery after a logical failure can often be attempted many times without effecting the media at all. This is because the technician is not having to open the chassis for a mechanical or electronic repair.

Hard drives are precision instruments and are not designed to be disassembled. Similarly donor parts are often not compatible. To provide a quote for a data recovery and file listing of recoverable files, our experts have already rebuilt the hard drive and recovered the data. Where quotes are declined we will always return the media to its original condition and return to the client. Yet just the fact that the drive has been disassembled means a subsequent attempt at recovery will be more complicated.

Most hard drives these days have multiple platters. To remove platters a specialist extraction tool is required. Platters are aligned to very exact specifications. The tracks are packed so tightly that the actuator is unlikely to pick them up after the chassis is opened, even though the user may not have touched the spindle! Platter extraction is a very delicate procedure on any hard drives over 20Gb in size. Once the rotational alignment of the platters has been altered – even by a hundredth of a millimetre - the game is more or less over unless you are prepared to spend big bucks!