Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T.) for Hard Disk Drives

S.M.A.R.T. is used to monitor computer hard disk drives and solid state drive, where it detects and reports on variety of indicators like drive reliability and predicts chances of the disks failing. When S.M.A.R.T. detects hardware failure the user has the option to replace the drive and minimize chances of data loss or expected outrage. The manufacturer is as well able to use the data that S.M.A.R.T. records to identify the faulty areas and minimize chances of occurrence or even completely prevent them from occurring with their future designs.

What to know about hard disk failures
There are two leading causes for hardware failures. The first one entails predictable failure that arises when its functionality slows down due to gradual degradation of storage components and mechanical wear of running components. With adequate monitoring it is easy to detect when failures such as these are likely to occur. The second type of failure is unpredictable failures in which the drive fails suddenly without any warning. Unpredictable failures may result when electronic components become defective because of sudden failures in its mechanical functionality.
Of the total cases of hard disk failure, 60 percent result from mechanical failures. As far as mechanical failure gets worse with time, most of the failures are caused by gradual wear of the running components and there may be indications that failure is on the way. Such indications include more generation of heat, making more noise, issues with data writing and reading and a large number of damaged disk sectors.

What information does S.M.A.R.T. provide?
The basic information provided by S.M.A.R.T. is the S.M.A.R.T. status. It provides just the information “threshold exceeded” and “threshold not exceeded”. In most instances these are represented as “drive fail” or “drive OK” respectively. The value for “threshold exceeded” indicates that there are high chances of the drive failing to be consistent with its specification in upon sometime in the future. The predicted failure may be serious, or just minor issue like being unable to write to some sectors, or at times slower performance that the minimum as per the manufacturer declaration.

The S.M.A.R.T. status may not always be indicative of the drive’s present or past reliability. If a drive has badly failed, the S.M.A.R.T. may not reflect. On the other end if the drive has had issues in the past, but its sensor can no longer detect similar problems, the S.M.A.R.T. status may as per the manufacturers programming report the drive’s status as being normal.

S.M.A.R.T. inability to read correctly some sectors may not mean the drive is almost failing. There are some instances that unreadable sectors will be created in the sectors even if the hard drive is normally functioning, one of them being when sudden power failure occurs as the drive is writing. On the other end, the physical may be damaged at some section, to the extent it cannot be readable, the disk may use the space in replacing the bad are, and that sector may be overwritten.

The health of a hard disk drive can also be obtained by examining S.M.A.R.T. attributes of a drive. Different manufacturers’ have different interpretations for the attributes, and in many instances is considered a trade secreted for the manufacturers.

As time goes, there are high chances for the drives with S.M.A.R.T. maintain some logs. The error log record information about the latest recorded errors that a disk reported to its host computer. By carefully examining the errors it can be determined whether the errors originate in a disk or another thing.

A drive implementing S.M.A.R.T. is likely to implement a series of maintenance or self rest routines, and results of these tests are normally kept in the self-test log. Self test routines are critical in detecting unreadable sectors in a hard disk, as this will enable them to be restored from backups. This is known to greatly minimize the chances of completely losing data.

S.M.A.R.T. drives self tests
There are a number of self tests provided by S.M.A.R.T. as highlighted next:

It checks the mechanical and electrical performance of a disk, and the disk’s read performance. The electrical tests conducted in clued data transfer circuitry test, testing of the buffer RAM, or testing the data transfer head elements. The mechanical tests did here include servo and seeking on the disk’s data tracks. Also checks pending sectors containing read errors and this takes less than two minutes.

Extended or long
This is a longer and more intensive version of the short scan test that scans the whole disk surface without time limit. May take many minutes, with a speed of 1 Gb per minute for the latest drives.

This is a quick test for identifying the damages that may have occurred when transporting device from drive manufacturer to computer manufacturer. The feature is available for limited number of drives and that takes many minutes.

There are a number of drives which allow some self tests on few parts of the surface.

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