Recovery of Data from Erroneous Magnetic Media

The disk imaging tool coupled with the analyser has proven to be a very powerful technology. One of its great benefits is that we have been able to read disks that are no longer readable by normal means.

Sources of Error

There are three different sources of errors on magnetic disks:

  • Physical damage - cannot be generally be recovered, at least not without very expensive processes and systems, and probably not even then.
  • Alien particles - bits of dust or dirt on the disk surface that prevents the drive head from getting a good read of the data.
  • Reading problems - there are lots of reasons why there can be problems reading a disk. In very basic terms the data and the system trying to read it are not idealy suited for reading. This can be further complicated by the age of both system and media.
  • Bit Rot - disks succumbing to bitrot are likely to start off looking like reading problems - up until the time when they can not longer be read at all.

The point is that many games can still be preserved even if they no longer appear to work. Whether a disk has real errors or just has reading problems is not evident until we succeed in getting a good disk image. Often we will not even notice that the game had problems loading in your system, because it was imaged correctly the first time.

If we did not get a good image of a disk it will be immediately apparent in the analyser and a redump will be requested. No disk images with errors can be preserved.

If this happens we gently urge you to use the Spin and Blow Technique as described below. This will hopefully remove any alien particles from the media. We also urge you to try imaging the disk on a different system or at best, a different drive to help negate any reading problems that may have occured.

Spin and Blow Technique

Here is a little tip that seems to be about 50% successful in getting a good read of disks that initially look to be damaged. Obviously it is at your own risk, but we think it is quite safe - we have not yet made a disk any worse - and we have done it to hundreds of disks.

Ideally, you will need to get a can of compressed air though it is possible to do without. You can blow with your mouth instead but you should be careful not to spit, and also be aware that you are basically putting water vapour on the disk surface. It is extremely unlikey you will do any damage to the disk this way, but it is obviously your own responsibility. Certainly you should make sure that the disk is completely dry before you put it into your disk drive!

What you need to do is open the metal shutter of the disk (perhaps you can even see dust or dirt on the disk surface) and blow the air inside the disk while turning the magnetic part around 360 degrees. Then do it again for the other side. You really need three hands for this, so you might want to get somebody to help you.

Sometimes this is just not enough to shift alien matter from the disk surface. So sometimes we use some cotten buds dipped in alchohol to clean it. If a disk has an error, then we might as well since the disk is otherwise useless for our purposes.

Whether you want to go that far is entirely up to you.