Hard Disk Drive Repair and Diagnostics
During the normal work hard disk drive keeps journal of unstable sectors which reassigned into the more reliable area during the self-test. The duration of full diagnostics depends on hard drive capacity: at the average, the diagnostics takes 1 hour. The hard disk drive activity LED indicator doesn't light during its execution though acoustic noise of disk activity occurs. Hard disk drive self-test is executed in a background mode without loading of the central processor unit. Since data is not transferred through interface cable, the internal self-test is the best way of analysis and repair of hard disk drives showing the best result in quality and speed in comparison with any programmatic methods.
Internal autonomous hard disk drive tests are launched by standard ATA/ATAPI commands. They are intended for deep analysis of hard disk drive mechanics and magnetic disks surface state. After the tests execution the hard disk drive without fail refreshes SMART indicators correspondingly to its current state.
Fast self-test tests only electronic components and positioning system of the hard disk drive that allows quickly to estimate their reliability: it takes 1 minute at average. Full self-test performs analysis of the hard disk drive magnetic surface by data reading by artificially lowered sensitivity of magnetic heads that allows to detect outlined defects, and by following writing into the same area, carrying out magnetic reversal that positively affected on data storage reliability since magnetized areas degauss with the lapse of time.