Most well-managed firms ensure that critical data is backed up, but some may still occasionally need to call on a data recovery firm. These can undertake a variety of tasks, from restoring deleted files on a Flash card to gleaning data from damaged Raid arrays.

Frank Priest, general manager of CBL Data Recovery Technologies, noted that even large companies can find that they have lost data. “Often you only find out something’s wrong with your backup when you try to restore the data,” he said, adding that there may also be a window of risk in which newly acquired data is not backed up.

We took the opportunity to test out the service offered by CBL when a laptop hard drive was damaged in a genuine accident. A user had tripped over an Ethernet cable, resulting in a sudden lateral tug and an impact with the floor. The drive, a 40GB Hitachi Travelstar, contained several gigabytes of Office documents plus numerous application and configuration files. After the accident, Windows froze and would not reboot because of missing files. After booting from an external disk, the drive initially responded to software repair attempts, but quickly ceased functioning altogether.

According to Priest, this kind of progressive failure is common. “If a head-crash creates debris it will lead to further damage,” he said.

Priest’s advice for firms is not to attempt their own repairs if a disk is making unusual noises. “Also, never open the drive. You’ll make matters a hundred times worse,” he warned. CBL has a clean room at its Newcastle base where disks can be safely disassembled.

Often, damaged heads can be replaced before reading data from undamaged parts of the platter. The latest hard drives with very high data densities and fast spin speeds can be problematic because a head crash may remove a large volume of data. “If certain critical parts of the drive are damaged – where the drive stores its own deep internal data – then you are left with a 50-million piece jigsaw that may be unrecoverable,” Priest said.

System software can also affect recoverability. “When it deletes a file, the Ext3 file system removes critical pointers. Under NTFS it’s much easier to recover deleted files,” Priest added.

Our disk was sent to CBL by post, and the next day we received an email stating that it was being evaluated. CBL does not charge for this, and also offers a “no data, no fee” policy. The next working day, CBL sent a PDF document offering a diagnosis – “motor bearing failure; minor head crash” – and an estimate that recovery would take 10 days and cost £850 plus VAT. The PDF included a contract for signing and CBL’s data privacy guarantee.

Costs vary with the complexity of the job, rather than the volume of data, and range from £100 for a Flash card to £5,000 or more for a server disk. CBL also offers a premium-rate fast-track service.

We chose the standard service and after 11 working days 99 percent of the data had been recovered. DVDs containing self-extracting archives arrived by post, unzipping to yield all the data necessary to restore user files and configurations, arranged in the original file structures.

CBL keeps drive images for two weeks unless requested otherwise. Customers can have the original media returned, or CBL can certify that it has been destroyed.