Miracle Workers: rescuing data from the jaws of disaster

Clean room

If a hard disk isn't working and can't be imaged in the pre-diagnosis area, it heads into the clean room. The engineers within will first listen to the disk and - using their considerable experience - will be able to determine whether it's safe to remove its lid or not. Some disks' chassis are integral to the spindle so opening it can render the disk useless as it can't be spun up or reassembled.

The clean room is equipped with special benches which prevent any dust or debris falling on the platters. Disks which are deemed safe to open have their lids removed and a visual inspection is carried out to check for problems. Each platter surface is inspected for damage as this can vary between platters.

We submitted our own damaged disk to Ontrack for assessment. Our disk, which spun up but refused to show up on the BIOS, had only minor damage on the upper surface of the platter.

IT Pro's damaged laptop hard disk

IT Pro's damaged laptop hard disk

IT Pro's damaged laptop hard disk

Unfortunately, the underside had a spiral scratch due to the head being in contact with the platter as it returned to it's parked position - a classic sign of a disk that has been dropped while operating. This kind of damage means the data can't be recovered from that platter.

If the data lost is mission critical, it may be possible to recover data from platters with minor damage. Ontrack's software allows the engineers to move the heads to a safe, undamaged area in order to copy the 'good' data off before attempting to image the damaged area. Allowing the heads to read the damaged area could cause further damage and destroy good data.

If a particular platter is beyond repair, the software can tell the disk to ignore any data being read from that platter's read/write head in order to trick the disk into thinking it is working correctly - otherwise it may refuse to read any data at all.