Self-Monitoring, Analysis and Reporting Technology Guide, Meaning , Facts, Information and Description

hard disk 

Self-Monitoring, Analysis, and Reporting Technology or S.M.A.R.T. is a monitoring tool for computer hard disks to see and report on various indicators of reliability, in the hope of anticipating failures.

There are fundamentally two classes of hard drive failures:

• Predictable - Some failure modes, especially mechanical wear and aging, happen gradually over time. These can be detected, much as a temperature dial on the dashboard of an automobile can warn the driver that the engine is overheating before serious damage occurs.
• Unpredictable - Other failures are sudden and unpredictable.

Approximately 60 percent of hard drive failures can be predicted by monitoring the drive's behavior. The goal of S.M.A.R.T. technology is to warn a user or system administrator of impending drive failure while there is still time to take preventive action, such as copying the data to a replacement device.

As an example, here is a list of the S.M.A.R.T attributes that are monitored by a WDC800JB-00CRA1 80-gigabyte hard drive:

• Raw Read Error Rate
• Spin Up Time
• Start/Stop Count
• Reallocated Sector Count
• Seek Error Rate
• Power On Hours Count
• Spin Retry Count
• Recalibration Retry Count
• Power Cycle Count
• Reallocation Event Count
• Current Pending Sector Count
• Uncorrectable Sector Count
• CRC Error Count
• Write Error Count

Note that drive temperature is not among the parameters reported by the drive, because it lacks a temperature sensor. Many other drives do include temperature sensors.

S.M.A.R.T was pioneered by Compaq (which merged with HP in 2002), and is now supported by most major hard drive and motherboard vendors. Most current motherboards will display a warning message when the disk drive is near failure.

There are also various monitoring programs that can be used to keep closer track of a disk drive's health. Each disk maker defines a set of attributes which the controller monitors, and also defines threshold values for these attributes that should not be reached in normal operation. Suitable software can keep track of these parameters over time, in order to extrapolate the current trends and predict when a "threshold exceeded condition" is likely to occur. Also, the software can distinguish between gradual degredation over time, representing normal wear, versus a sudden change which may indicate a problem.

External Links

• [1]
• [1]
• Hard disk Specification IBM Deskstar 40GV & 75GXP
• Website for one S.M.A.R.T. monitoring utility
• smartmontools - open-source monitoring utility

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