Hard drive data degrades over time. This phenomenon is called bit-rot. Defects in the hard drive could grow over time. Nowadays, storage disk manufacturers are having a big problem due to high competition to fit more and more data onto available disk surface area. Error correction mechanisms take a back seat in this rat race. As the size of a bit representation in the hard drive gets smaller and smaller, any defect in the hard drive surface area gets larger and larger. When the accumulated defects reaches critical mass, the hard drive reader could no longer successfully correct errors in the data stored and the data read fails.
Spinrite is a mass storage disk maintenance and data recovery tool developed by GRC.
Spinrite, in maintenance mode, is capable of exercising the surface of a mass storage device to find out spots of defects. When it spots a defective sector with growing error rate, which is but still below the threshold point-of-no-return, it moves the sector to a healthy location on the hard disk as a proactive preventive measure.
Spinrite, in data recovery mode, is able to employ a variety of methods to try to recover data from sectors that have already crossed the threshold point-of-no-return, as per the mass storage management system’s capabilities (including trying to read the sector using different head speeds, head angles, making intelligent interpolations and assumptions of data, etc).