Intro the Technology of S.M.A.R.T.

What does S.M.A.R.T. stand for?
Computer users today have great expectations of data storage reliability. The S.M.A.R.T. is "Self Monitoring And Reporting Technology".It is a standard interface allowing a hard disk drive to check its status, report it to host system, and provide some estimation for a failure date to allow a system, or user, to back up data prior to a drive's failure.

What is the S.M.A.R.T. attribute?
S.M.A.R.T attribute is a specific property(parameter) of disk being monitored. The attribute is referred to either by its number or by its descriptive name. Attribute value is a positive integral number, usually in range from 1 to 100 (or sometimes 1 to 200). Maximum values are good, minimum values indicate that some component of the disk is about to fail. Specific treshold is assigned to each attribute. Once the value drops below this threshold, S.M.A.R.T considers disk to be faulty. Some attributes are considered life-critical and others are merely "informative". (e.g.: the "Temperature" attribute indicates the temperature of the hard disk, the "Power-On Hours" attribute indicates the count of hours in a power-on state, etc.) Various manufacturers may use different sets of attributes.

Some failures are predictable, and some are not.
A disc drive must be able to monitor many elements in order to have a comprehensive reliability management capability. One of the most crucial elements is understanding failures. Failures can be seen from two standpoints: predictable, and unpredictable.

Unpredictable failures occur quickly, like electronic and mechanical problems, such as a power surge that can cause chip or circuit failure.

Predictable failures are characterized by degradation of an attribute over time, before the disc drive fails. This creates a situation where attributes can be monitored, making it possible for predictive failure analysis.Mechanical failures, which are mainly predictable failures, account for 60 percent of drive failure. With the emerging technology of S.M.A.R.T., an increasing number of predictable failures will be predicted, and data loss will be avoided.