Platter Scratch Repairing – The Critical Step Into Data Recovery From Crashed Drives

Take the case of computer systems. We become so used to working on the computer on a regular basis that we are rarely ready to face the consequences if things go wrong. This is truer of a computer hard disk drive crash than of anything else. Hard drive malfunction can be divided into two types: one is the so called Firmware Level malfunction that can be repaired using relating software or factory commands; the other one left is the Physical Level malfunction caused by physical hard drive components damage. As to the latter Physical Level crash, the typical case in data recovery practices is that the head crash and serious platter scratches caused by direct contact between the head and the platter surface; such drives manifest themselves as undetected, staying BUSY, besides an ominous scratching sound may start to emanate from the disk. This is a serious problem. It is indicative of nothing less than a crash of the hard disk drive.

Functioning of a Hard Disk Drive

In order to understand the problem of a hard disk drive crash, it is important to first understand the mechanism of a hard drive. Only after knowing how the disk drive functions can one understand the nature of the problem.


Read-Write Head: The read-write heads of the hard disk drives are those mechanisms that, as the name suggests read or write the data from the magnetic fields of the platters.

Hard Disk Platter: A hard disk platter is a circular disk within the hard disk drive. It is circular in shape and the magnetic media of the disk drive is stored on it. Generally multiple platters are mounted on a single spindle of the hard disk drive.

Lubricant Layer: This is the topmost layer of the platters and is made of a substance similar to Teflon.
Carbon: There is a layer of sputtered carbon just below the lubricant layer.
Magnetic Layer: This is below the layer of carbon.


The magnetic layer of the hard disk drive stores all the data. The two layers of carbon and the lubricant like material saves this magnetic layer from coming into accidental contact with the read-write head of the disk, we can say they exist as the protection layer of the magnetic layer (of course, another important function of them is to maintain the stability of the flying read-write head)

The platters move at an exceptional speed and the data is read from, or written on to, the magnetic layer by the read-write head which flies above the surface of the platter. As the read-write head flies over the platter surface its height is controlled by a thin film or layer of air entrapped between the platters and the slider surface of the read-write head. That’s why we mentioned that one of the functions of the protection layer is to maintain the stability of the flying read-write head: the film of air floats the head over the surface will be generated only when the surface of the platter maintains flat and smooth.

If the read-write head comes into direct contact with the surface of the disk platters then the head can scratch through the protective layers of sputtered carbon and the lubricant material, leaving a circle scratch area to the platter. This is called a head crash or a hard disk drive platter crash.

Cause of a Hard Disk Drive Crash

The cause of a head crash can be a minute particle causing the read-write head to bounce against the platter disk. The head is made of hard materials that can scratch through all the protective layers. If the head bounces against the platter while the latter is rotating at a speed equivalent to thousands of revolutions per minute then the head is bound to scratch the platter surface. This destroys the magnetic layer of the platters. If the head begins to drag over the platter then the data loss can be tremendous. Besides this the head will end up overheating or physical damage making the hard disk drive stop functioning properly. Even the possibility of further head crashes increases as particulate freed on account of one head crash are scraped on to the platter surface, leaving more scratches to the platter each time you power up the drive.

Data recovery from drives with physical scratches

For data recovery from physically damaged (head crash/platter scratch) hard drive, currently the best and the only solution is to open the HAD in a proper environment (such as a clean room) to replace the damaged physical head stack, meanwhile to clean up the particles on the platter, then working for data recovery from the postoperative drive. However this technique will not work for all the cases, especially when there are severe scratch area on the platter which is caused by the head crash – besides a failed head swap, the scratch area will also be an obstacle for your successful data recovery: even after you swap the crashed head stack faultlessly, it will crash immediately on power up, making the scratch issue worse and there is no way for users to read any data (even the data locate on good area of the platter) out of the drive. The reason for this situation is that when the head flies over the scratch area (it does not matter if it is trying to read from that area or not), due to the breakage of the protective layers, the head can no longer maintain its floating status when it comes to the scratch area, but makes directly contact with the platter again, the head will end up overheating or physical damage (crash or short circuit). The point of how to recover data from the patient drive becomes the point of how to make sure the head passes the scratch area smoothly.

Platter Scratch Restoration Solution

What is Platter Scratch Restoration Solution?
The Platter Scratch Restoration Solution is the unique technology developed under joint effort of SalvationDATA, Computer Institution of CAS, Chemistry Institution of CAS and Physics Institution of CAS, which takes over two years of time and hundreds of thousands of dollars for R&D, integrating interdisciplinary achievements of multiple fields like chemistry, computer application and physics. It is the perfect solution for the current corner of data recovery from drives with severe platter scratch; empowering data recovery professionals who have been working on physical data recovery a deeper and more comprehensive capability.

Basic principles of operation:
SalvationDATA Platter Scratch Restoration System includes the following major parts:

1. High precision scratch positioner
2. High pressure cleaner
3. Nanometer filling materials spray arm
4. Master program controller

The system will first clean up the target platter using the high pressure air cleaner; then scan the platter with the optical scratch positioner to locate scratch area and label its size and depth; finally the spray arm contains the nanometer filling materials will fill the scratch area with the donor materials under the management of the master program controller, so as to restore the scratches and make the scratch area revert to flat and smooth, thereby allows the head to pass the scratch area in a stable floating status so that data recovery from the good area can be achieved. The scratch positioner carries out analysis and positioning towards the tiny scratches using optical imageology technology; by sending the scan report back to the master program controller, a repairing instruction flow will be generated and sent to the spray arm controller for implementation. The nanometer filling materials and the high precision nozzle controlled by the master program controller ensures 100% accuracy of the restoration; meanwhile the filling materials have been improved by trial and error, it won’t cause any chemical reaction with the materials of the different layers.

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