Stands for "Self-Monitoring Analysis and Reporting Technology."
SMART is a monitoring system that is built into hard disk drives and solid-state drives that detects and reports errors that may lead to drive failure. By providing a warning when errors are first detected, it can help prevent data loss by encouraging backing up and replacing a disk before it fails.
SMART monitors more than 80 attributes of a disk drive, such as its temperature, the time it takes to spin up, or the number of read or write errors that have been recorded. The manufacturer of a disk drive programs the SMART system with a threshold value for each attribute, so that SMART can provide an alert when one is outside of the normal range. A SMART warning can appear while a computer is booting (during POST), or as a notification through the computer's operating system.
A disk drive with a SMART system can perform two types of self test—a short Disk Self Test (DST), or a long DST. A computer runs a short DST on each disk when it boots, and the disk can still be used while the test runs. A long DST can be performed by disk management software built into the BIOS, the operating system, or provided by the manufacturer. A disk cannot be used during a Long DST, since it is a very resource-intensive process, but it is wise to run one periodically to check a disk's health.