S.M.A.R.T. (akronym för Self-Monitoring Analysis and Reporting Technology) är en funktion i vissa hårddiskar som gör det möjligt uppskatta tillståndet på dessa. Diagnostiken som görs varierar mellan olika hårddiskar, men innefattar ofta saker som att söktid och andel felläsningar ligger inom ett acceptabelt intervall. Antalet timmar hårddisken varit påslagen, antalet gånger den startat upp, och den högsta temperatur den blivit utsatt för är andra vanliga parametrar som kan läsas ut.
Vissa datorer visar en varning vid uppstart om dessa parametrar indikerar att något verkar fel. I sådana fall bör en backup omedelbart göras och hårddisken bytas ut då den har en klart ökad risk för att inom kort helt gå sönder och bli oläsbar.
Träffsäkerhet En fältstudie på Google som täckte över 100 000 enheter för konsumentklass från december 2005 till augusti 2006 hittade följande samband mellan viss SMART-information och årliga hårddiskhaverier: Under 60 dagar efter det första okorrigerbara felet på en enhet (SMART-data 198/0xC6) som upptäcktes genom en offline-skanning, var enheten 39 gånger i genomsnitt mer benägen att haverera, än en felfri enhet. Första registreringen av SMART-data för omlokalisering (5/0x05 och 196/0xC5) samt väntad omlokalisering (SMART-data 197/0xC5) var också starkt korrelerad med högre sannolikhet för haveri. Små samband för ökad temperatur och inget samband för användningsnivå. 56% av de havererade enheterna hade inget registrerat i något av de "fyra starka S.M.A.R.T.-varningarna" (läsfel eller olika typer av omlokaliseringsräknare). 36% av de havererade enheterna hade inga S.M.A.R.T.-fel alls, utom temperaturen, vilket innebär att S.M.A.R.T.-data ensamt bara ger begränsad möjlighet att förutse haveri.
ATA S.M.A.R.T.-attribut Varje tillverkare definierar en uppsättning attribut, och sätter olika tröskelvärden för attribut som inte ska passera under normal drift. Varje attribut har ett råvärde(RAW) i decimal- eller hexadecimal form vars betydelse bestäms av drivenhetstillverkaren. Dessa råvärden står för antal gånger något har är inträffat, drifttimmar, uppstarter, temperatur, söktider, time-outer, läsfel, överförda datamängder, etc. Viktigare är att avläsa aktuellt attributvärde i förhållande till sämsta uppmätta värde och tröskelvärde, ofta uttryckt i skalor 252→0, 200→0 eller 100→0, där högt aktuellt värde är bäst.
Tillverkare som har implementerat minst ett S.M.A.R.T.-attribut i olika produkter inkluderar Samsung, Seagate, IBM (Hitachi), Fujitsu, Maxtor, Toshiba, Intel, sTec, Inc., Western Digital och ExcelStor Technology.
Kända ATA S.M.A.R.T.-attribut Följande diagram visar några S.M.A.R.T.-attribut och den typiska betydelsen av deras råvärden. Normaliserade värden kartläggs vanligtvis så att de högre värdena är bättre (undantag inkluderar körtemperatur, antal läshuvudbelastningar-/avlastningscykler), men högre RAW-värden kan vara bättre eller sämre beroende på attributet och tillverkaren. Till exempel attributet "Reallocated Sectors Count/Antal omlokaliserade sektorer" aktuella normaliserade värde minskar när antalet omlokaliserade sektorer ökar. I detta fall indikerar attributets "RAW"-värde ofta antalet sektorer som har omfördelats, även om leverantörer inte på något sätt säger sig följa denna konvention.
Eftersom tillverkare inte nödvändigtvis håller med om exakta attributdefinitioner och mätenheter, är följande lista med attribut bara en allmän guide.
Enheter stöder inte alla attributkoder (ibland förkortade "ID", för "identifierare", i tabeller). Vissa koder är specifika för specifika drivenheter (magnetisk tallrik, blixt, SSD). Enheter kan använda olika koder för samma parameter, se till exempel koder 193 och 225.
+ Legend/Teckenförklaring ID 1930xC1Attribut i decimal ochhexadecimal form Önskvärt Högre RAW-värde är bättre. Lägre RAW-värde är bättre. !(Kritisk)
Kritiskt attribut.Specifika värden kan förutse enhetshaveri.
ID Attribut Önskvärt ! Beskrivning 010x01 Read Error Rate (Vendor specific raw value.) Stores data related to the rate of hardware read errors that occurred when reading data from a disk surface. The raw value has different structure for different vendors and is often not meaningful as a decimal number. 020x02 Throughput Performance Overall (general) throughput performance of a hard disk drive. If the value of this attribute is decreasing there is a high probability that there is a problem with the disk. 030x03 Spin-Up Time Average time of spindle spin up (from zero RPM to fully operational [milliseconds]). 040x04 Start/Stop Count A tally of spindle start/stop cycles. The spindle turns on, and hence the count is increased, both when the hard disk is turned on after having before been turned entirely off (disconnected from power source) and when the hard disk returns from having previously been put to sleep mode. 050x05 Reallocated Sectors Count Count of reallocated sectors. The raw value represents a count of the bad sectors that have been found and remapped. Thus, the higher the attribute value, the more sectors the drive has had to reallocate. This value is primarily used as a metric of the life expectancy of the drive; a drive which has had any reallocations at all is significantly more likely to fail in the immediate months. 060x06 Read Channel Margin Margin of a channel while reading data. The function of this attribute is not specified. 070x07 Seek Error Rate (Vendor specific raw value.) Rate of seek errors of the magnetic heads. If there is a partial failure in the mechanical positioning system, then seek errors will arise. Such a failure may be due to numerous factors, such as damage to a servo, or thermal widening of the hard disk. The raw value has different structure for different vendors and is often not meaningful as a decimal number. 080x08 Seek Time Performance Average performance of seek operations of the magnetic heads. If this attribute is decreasing, it is a sign of problems in the mechanical subsystem. 090x09 Power-On Hours Count of hours in power-on state. The raw value of this attribute shows total count of hours (or minutes, or seconds, depending on manufacturer) in power-on state.
"By default, the total expected lifetime of a hard disk in perfect condition is defined as 5 years (running every day and night on all days). This is equal to 1825 days in 24/7 mode or 43800 hours."
On some pre-2005 drives, this raw value may advance erratically and/or "wrap around" (reset to zero periodically). 100x0A Spin Retry Count Count of retry of spin start attempts. This attribute stores a total count of the spin start attempts to reach the fully operational speed (under the condition that the first attempt was unsuccessful). An increase of this attribute value is a sign of problems in the hard disk mechanical subsystem. 110x0B Recalibration Retries or Calibration Retry Count This attribute indicates the count that recalibration was requested (under the condition that the first attempt was unsuccessful). An increase of this attribute value is a sign of problems in the hard disk mechanical subsystem. 120x0C Power Cycle Count This attribute indicates the count of full hard disk power on/off cycles. 130x0D Soft Read Error Rate Uncorrected read errors reported to the operating system. 220x16 Current Helium Level Specific to He8 drives from HGST. This value measures the helium inside of the drive specific to this manufacturer. It is a pre-fail attribute that trips once the drive detects that the internal environment is out of specification. 1700xAA Available Reserved Space See attribute E8. 1710xAB SSD Program Fail Count (Kingston) The total number of flash program operation failures since the drive was deployed. Identical to attribute 181. 1720xAC SSD Erase Fail Count (Kingston) Counts the number of flash erase failures. This attribute returns the total number of Flash erase operation failures since the drive was deployed. This attribute is identical to attribute 182. 1730xAD SSD Wear Leveling Count Counts the maximum worst erase count on any block. 1740xAE Unexpected power loss count Also known as "Power-off Retract Count" per conventional HDD terminology. Raw value reports the number of unclean shutdowns, cumulative over the life of an SSD, where an "unclean shutdown" is the removal of power without STANDBY IMMEDIATE as the last command (regardless of PLI activity using capacitor power). Normalized value is always 100. 1750xAF Power Loss Protection Failure Last test result as microseconds to discharge cap, saturated at its maximum value. Also logs minutes since last test and lifetime number of tests. Raw value contains the following data: Bytes 0-1: Last test result as microseconds to discharge cap, saturates at max value. Test result expected in range 25 <= result <= 5000000, lower indicates specific error code. Bytes 2-3: Minutes since last test, saturates at max value. Bytes 4-5: Lifetime number of tests, not incremented on power cycle, saturates at max value.
Normalized value is set to one on test failure or 11 if the capacitor has been tested in an excessive temperature condition, otherwise 100.1760xB0 Erase Fail CountS.M.A.R.T. parameter indicates a number of flash erase command failures. 1770xB1 Wear Range Delta Delta between most-worn and least-worn Flash blocks. It describes how good/bad the wearleveling of the SSD works on a more technical way. 1790xB3 Used Reserved Block Count Total "Pre-Fail" attribute used at least in Samsung devices. 1800xB4 Unused Reserved Block Count Total "Pre-Fail" attribute used at least in HP devices. 1810xB5 Program Fail Count Total or Non-4K Aligned Access Count Total number of Flash program operation failures since the drive was deployed. Number of user data accesses (both reads and writes) where LBAs are not 4 KiB aligned (LBA % 8 != 0) or where size is not modulus 4 KiB (block count != 8), assuming logical block size (LBS) = 512 B. 1820xB6 Erase Fail Count "Pre-Fail" Attribute used at least in Samsung devices. 1830xB7 SATA Downshift Error Count or Runtime Bad Block Western Digital, Samsung or Seagate attribute: Either the number of downshifts of link speed (e.g. from 6Gbps to 3Gbps) or the total number of data blocks with detected, uncorrectable errors encountered during normal operation. Although degradation of this parameter can be an indicator of drive aging and/or potential electromechanical problems, it does not directly indicate imminent drive failure. 1840xB8 End-to-End error / IOEDC This attribute is a part of Hewlett-Packard's SMART IV technology, as well as part of other vendors' IO Error Detection and Correction schemas, and it contains a count of parity errors which occur in the data path to the media via the drive's cache RAM. 1850xB9 Head Stability Western Digital attribute. 1860xBA Induced Op-Vibration Detection Western Digital attribute. 1870xBB Reported Uncorrectable Errors The count of errors that could not be recovered using hardware ECC (see attribute 195). 1880xBC Command Timeout The count of aborted operations due to HDD timeout. Normally this attribute value should be equal to zero. 1890xBD High Fly Writes HDD manufacturers implement a flying height sensor that attempts to provide additional protections for write operations by detecting when a recording head is flying outside its normal operating range. If an unsafe fly height condition is encountered, the write process is stopped, and the information is rewritten or reallocated to a safe region of the hard drive. This attribute indicates the count of these errors detected over the lifetime of the drive.