What is Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.)

The ATA-3 interface includes logic called S.M.A.R.T., which stands for Self Monitoring Analysis and Reporting Technology. S.M.A.R.T. helps predict when a hard drive is going to fail by monitoring the hard drive’s mechanical components. When S.M.A.R.T. is enabled for a given drive, the drive monitors predetermined attributes that are susceptible to or indicative of drive degradation. Based on changes in the monitored attributes, a failure prediction can be made.

S.M.A.R.T. makes a status report available so the system BIOS or driver software and the operating system can notify the user of the impending problems, perhaps enabling the user to back up the data on the drive before any real problems occur.

S.M.A.R.T. is designed to predict mechanical drive failures. Not all failures are predictable by S.M.A.R.T. These can be caused by static electricity, improper handling or sudden shock, or circuit failure (such as thermal-related solder problems or component failure).

S.M.A.R.T. is a technology that periodically measures selected drive attributes and sends a warning message when a predefined threshold is exceeded. The S.M.A.R.T. specification placed in the public domain covers both ATA and SCSI HDDs and can be found in most of the more recently produced drives on the market.

The S.M.A.R.T. design of attributes and thresholds is similar in ATA and SCSI environments, but the reporting of information differs.

The driver polls the drive on a regular basis to check the status of the S.M.A.R.T. 'report status' command and, if it signals imminent failure, sends an alarm to the OS where it is passed on via an error message to the end user. SCSI drives with S.M.A.R.T. communicate a reliability condition only as good or failing. In a SCSI environment, the failure decision occurs at the disk drive and the host notifies the user for action.

Drives with S.M.A.R.T. monitor a variety of attributes that vary from one manufacturer to another. Attributes are selected by the device manufacturer based on their capability to contribute to the prediction of degrading or fault conditions for that particular drive. Most drive manufacturers consider the specific set of attributes being used and the identity of those attributes as vendor specific and proprietary. Some of the attributes monitored on various drives include the following:

• Head floating height
• Data throughput performance
• Spin-up time
• Reallocated (spared) sector count
• Seek error rate
• Seek time performance
• Drive spin-up retry count
• Drive calibration retry count

Each attribute has a threshold limit that determines the existence of a degrading or fault condition. These thresholds are set by the drive manufacturer, can vary among manufacturers and models, and can’t be changed.

What is Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) UQi3Piu

When sufficient changes occur in the monitored attributes to trigger a S.M.A.R.T. alert, the drive sends an alert message via an IDE/ATA or a SCSI command (depending on the type of HDD you have) to the hard disk driver in the system BIOS, which usually reports the problem during the POST the next time the system boots.

If you want more immediate reporting, you can run a utility that queries the S.M.A.R.T. status of the drive, for the best health S.M.A.R.T. report of your drive use that drive manufacturer drive diagnostic software. If you receive a S.M.A.R.T. warning first thing to do is to back up all the data on the drive.

S.M.A.R.T. warnings can be caused by an external source and might not actually indicate that the drive is going to fail. For example, environmental changes such as high or low ambient temperatures can trigger a S.M.A.R.T. alert, as can excessive vibration in the drive caused by an external source. Additionally, electrical interference from motors or other devices on the same circuit as your PC can induce these alerts. If the alert was not caused by an external source, drive should be replaced.

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