Data degradation

Data degradation is the gradual corruption of computer data due to an accumulation of non-critical failures in a data storage device. The phenomenon is also known as data decay or data rot.

Data degradation in dynamic random-access memory (DRAM) can occur when the small electric charge of a bit in DRAM disperses, possibly altering program code or stored data. Semiconductor RAM may also occasionally be altered by cosmic rays or other high-energy particles. Such data degradation is known as soft errors. Different variants of ECC memory can be used to mitigate this type of data degradation.

Data degradation can also be used to describe the phenomenon of storage media gradually decaying over the duration of many years. The cause of data decay varies depending on the medium:

Most disk, disk controller and higher-level systems are subject to a small degree of unrecoverable failure. With ever-growing disk capacities, file sizes, and increases in the amount of data stored on a disk, the likelihood of the occurrence of data decay and other forms of uncorrected and undetected data corruption increases.

Higher-level software systems may be employed to mitigate the risk of such underlying failures by increasing redundancy and implementing integrity checking and self-repairing algorithms. The ZFS file system was designed to address many of these data corruption issues. The Btrfs file system also includes data protection and recovery mechanisms, and so does ReFS.

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