Bad Sectors with Degraded Head

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The basic unit of data storage on a device is referred to as a ‘sector’.  Historically, a sector on a hard drive contains 512 bytes of information (equivalent in size to a text message containing 512 characters).  Modern drives can use larger-sized basic storage blocks, equivalent in size to 8 traditionally-sized sectors.

Each sector has a unique address, and this is how your system keeps track of where each file (or part of a file) is stored.  Files will usually span a number of sectors, in some cases adjacent to each other and in other cases fragmented (non-adjacent).

All hard drives contain an inherent quantity of bad (i.e. unusable) sectors when they leave the factory.  The drive maintains a list of these unusable locations and will never attempt to store data in these locations.

As time goes by during the working life of a hard drive, more sectors will become unreliable and unusable due to what are most easily described as ‘wear and tear’ effects related to the platter surface(s) in the hard drive.  In this case, the read/write mechanism is properly functioning, though the disk surface has degraded.  The hard drive also keeps track of these developing bad sectors.

The effect of proliferation of bad sectors will depend on what data is stored on those sectors and may range from ‘drive not recognised’ messages to clicking sounds from the drive.

Sectors store all data types, i.e. operating system files, file table, application files, data files etc.

This failure type is one where the file table is affected, which means that that a proportion of original folder structures and file names are lost.  Such ‘orphaned’ files/folders may still be recoverable, though will be named and grouped differently to their original file locations.

Some data corruption is expected with this failure type.

This is usually a resolvable failure, though the time required for data recovery varies directly with the quantity of bad sectors present, and their location on the hard drive.

CDS uses fault-tolerant hard drive reading systems that can read the drive content dynamically in order to bypass, correct or approximate bad sector content in order to facilitate a comprehensive data recovery of data from an affected hard drive.