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What is S.M.A.R.T
SMART is an acronym for S elf M anaging A nalysis R eporting T echnology. For many years, PC's or laptops have been delivered with a HD (Hard Drive). HD's contain a spindle motor to rotate the disk(s), and a positioning motor to locate heads over the disks. While the disks are spinning the heads detect or generate magnetic information on the media. Electronic devices and firmware in the HD are designed to monitor and/or tolerate marginal behavior of the HD components. The HD is also capable of reporting correctable or uncorrectable behavior. This implies the HD contains devices that manage the components in the HD. There is a standard known as SMART (Self Managing Analysis Reporting Technology) that defines data the HD can report about internal characteristics. There are programs for Windows and Linux that allow you to see SMART information. Some of the SMART data can indicate the HD should be considered for replacement before a catastrophic failure.
I am not aware of Windows or Linux paying much attention to SMART data in such a way as to warn the user before the HD is problematic. However, I have observed that a HD that is not accessible with Windows (will not boot or show data), does work “good enough” with Linux to allow access to SMART statistics and recovery of data.
You can see the SMART statistics for the HD in your computer. How? A program known as gsmartcontrol will display SMART statistics and allow you to invoke “Self Tests” on the HD. Gsmartcontrol is available for Windows and Linux. Here are some screenshots of what gsmartcontrol can produce. Once a HD has become problematic, it is not uncommon for Windows to be unable to boot to a condition where you can execute gsmartcontrol. In this case, booting from a USB instance of LInux may allow you to view SMART statistics with gsmartcontrol. Recovery of data may also be possible. If the HD will not boot, removing the HD from the computer and attaching it to another computer, as an additional HD, may allow you to recover data. Attachment to another computer can be done with USB or SATA.
SMART is hard
From a big picture perspective, the HD can be considered a computer that manages the devices in the HD. The devices are the motors, heads and disks. This implies that from the perspective of your computer, the HD behaves like a smart device (pun intended).
Having a way to look at SMART information is good, but… For the uneducated, making sense of the data is hard. Why? Because some errors are corrected by the HD before a command from the computer is completed by the HD. SMART data includes statistics that indicate corrected errors, that can precede the HD not being able to correct an error.
So how can a consumer differentiate between soft errors (errors that were corrected), hard errors (uncorrected errors) and soft errors that should indicate Replace The HD ?
Gsmartcontrol can display the contents of a LOG of HD events. If the LOG displayed by gsmartcontrol shows messages that are the color RED , the HD probably needs to be replaced.
SMART data includes statistics about corrected errors. Corrected errors can include positioning errors ( The HD determined that it positioned the heads in the wrong place) and media errors. (The HD determined a part of the disk surface is incapable of storing data).
A positioning error occurs when the HD detects the heads are in the incorrect position. How is this possible? When data is recorded on the media, part of the data includes the position of the data.
Media errors can be detected because the data on the media includes correction data. When data is read from the media, the HD verifies the data is good and/or try's to correct the data with the correction data. If a sector of media is determined to be bad, then the HD may reallocate spare sectors for a bad sector on the media. HD's have a finite number of spare sectors for reallocation. If the HD exhausts the supply of spare sectors, data may be lost.
This video demonstrates gsmartcontol. It starts a bit slow, but does cover the important features of the tool. Youtube video about gsmartcontrol.
Alternatives to GsmartControl
alternativeto.net identifies alternatives to gsmartcontrol
Vendor comments about SMART.
Seagate offers this comment: Seagate and SMART