一般VALUE是当前值，WORST是曾经最差值，THRESH是出厂设定值，如果VALUE接近THRESH（一般就是VALUE小于或者等于THRESH）的时候，而且TYPE是Pre-fail的，就表示硬盘差不多坏了。
ATA S.M.A.R.T. Attributes
Each drive manufacturer defines a set of attributes, and sets threshold values beyond which attributes should not pass under normal operation. Each attribute has a raw value, whose meaning is entirely up to the drive manufacturer (but often corresponds to counts or a physical unit, such degrees Celsius or seconds), and a normalized value, which ranges from 1 to 253 (with 1 representing the worst case and 253 representing the best). Depending on the manufacturer, a value of 100 or 200 will often be chosen as the “normal” value.
Manufacturers that have supported at least one S.M.A.R.T. attribute in various products include: Samsung, Seagate, IBM (Hitachi), Fujitsu, Maxtor, Toshiba, Western Digital and ExcelStor Technology.
[edit] Known ATA S.M.A.R.T. attributes
| This article may contain original research or unverified claims. Please improve the article by adding references. See the talk page for details. (September 2007) |
The following chart lists some S.M.A.R.T. attributes and the typical meaning of their raw values. Normalized values are always mapped so that higher values are better (with only very rare exceptions such as the “Temperature” attribute on certain Seagate drives[12]), but higher raw attribute values may be better or worse depending on the attribute and manufacturer. For example, the “Reallocated Sectors Count” attribute’s normalized value decreases as the number of reallocated sectors increases. In this case, the attribute’s raw value will often indicate the actual number of sectors that were reallocated, although vendors are in no way required to adhere to this convention. As manufacturers do not necessarily agree on precise attribute definitions and measurement units, the following list of attributes should be regarded as a general guide only.
| Legend | |||
|---|---|---|---|
| Higher raw value is better | Lower raw value is better | ||
| Critical | Potential indicators of imminent electromechanical failure | ||
| ID | Hex | Attribute name | Better | Description |
|---|---|---|---|---|
| 01 | 01 | Read Error Rate | Indicates the rate of hardware read errors that occurred when reading data from a disk surface. A non-zero value indicates a problem with either the disk surface or read/write heads. Note that Seagate drives often report a raw value that is very high even on new drives, and does not thereby indicate a failure. | |
| 02 | 02 | 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. | |
| 03 | 03 | Spin-Up Time | Average time of spindle spin up (from zero RPM to fully operational [millisecs]). | |
| 04 | 04 | Start/Stop Count | A tally of spindle start/stop cycles. | |
| 05 | 05 | Reallocated Sectors Count | Count of reallocated sectors. When the hard drive finds a read/write/verification error, it marks this sector as “reallocated” and transfers data to a special reserved area (spare area). This process is also known as remapping, and “reallocated” sectors are called remaps. This is why, on modern hard disks, “bad blocks” cannot be found while testing the surface – all bad blocks are hidden in reallocated sectors. However, as the number of reallocated sectors increases, the read/write speed tends to decrease. The raw value normally represents a count of the number of bad sectors that have been found and remapped. Thus, the higher the attribute value, the more sectors the drive has had to reallocate. | |
| 06 | 06 | Read Channel Margin | Margin of a channel while reading data. The function of this attribute is not specified. | |
| 07 | 07 | Seek Error Rate | 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. More seek errors indicates a worsening condition of a disk’s surface or the mechanical subsystem, or both. Note that Seagate drives often report a raw value that is very high, even on new drives, and this does not normally indicate a failure. | |
| 08 | 08 | 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. | |
| 09 | 09 | Power-On Hours (POH) | 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. | |
| 10 | 0A | 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. | |
| 11 | 0B | Recalibration Retries | This attribute indicates the number of times recalibration was requested (under the condition that the first attempt was unsuccessful). A decrease of this attribute value is a sign of problems in the hard disk mechanical subsystem. | |
| 12 | 0C | Device Power Cycle Count | This attribute indicates the count of full hard disk power on/off cycles. | |
| 13 | 0D | Soft Read Error Rate | Uncorrected read errors reported to the operating system. If the value is non-zero, you should back up your data. | |
| 189 | BD | High Fly Writes (WDC) | Fly Height Monitor Improves Hard Drive Reliability. Western Digital’s Fly Height Monitor protects 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 constant monitoring process increases the reliability of write operations and reduces the probability of read errors.The new Fly Height Monitor is being implemented in Western Digital’s drives, beginning with the WD Enterprise WDE18300 and WDE9180 Ultra2 SCSI hard drives, and will be included on all future WD Enterprise products.(http://www.wdc.com/en/library/2579-850123.pdf) | |
| 190 | BE | Airflow Temperature (WDC) | Airflow temperature on Western Digital HDs (Same as temp. [C2], but current value is 50 less for some models. Marked as obsolete.) | |
| 190 | BE | Temperature Difference from 100 | Value is equal to (100 – temp. °C), allowing manufacturer to set a minimum threshold which corresponds to a maximum temperature.(Seagate only?)[citation needed] Seagate ST910021AS: Verified Present[citation needed] Seagate ST9120823ASG: Verified Present under name “Airflow Temperature Cel” 2008-10-06 Seagate ST3802110A: Verified Present 2007-02-13[citation needed] Seagate ST980825AS: Verified Present 2007-04-05[citation needed] Seagate ST3320620AS: Verified Present 2007-04-23[citation needed] Seagate ST3500641AS: Verified Present 2007-06-12[citation needed] Seagate ST3250824AS: Verified Present 2007-08-07[citation needed] Seagate ST31000340AS: Verified Present 2008-02-05[citation needed] Seagate ST3160211AS: Verified Present 2008-06-12[citation needed] Seagate ST3320620AS: Verified Present 2008-06-12[citation needed] Seagate ST3400620AS: Verified Present 2008-06-12[citation needed] Samsung HD501LJ: Verified Present under name “Airflow Temperature” 2008-03-02[citation needed] Samsung HD753LJ: Verified Present under name “Airflow Temperature” 2008-07-15[citation needed] |
|
| 191 | BF | G-sense error rate | Frequency of mistakes as a result of impact loads[citation needed] | |
| 192 | C0 | Power-off Retract Count | Number of times the heads are loaded off the media. Heads can be unloaded without actually powering off.[citation needed] (or Emergency Retract Cycle count – Fujitsu)[citation needed] | |
| 193 | C1 | Load/Unload Cycle | Count of load/unload cycles into head landing zone position.[citation needed] | |
| 194 | C2 | Temperature | Current internal temperature. | |
| 195 | C3 | Hardware ECC Recovered | Time between ECC-corrected errors.[citation needed] | |
| 196 | C4 | Reallocation Event Count | Count of remap operations. The raw value of this attribute shows the total number of attempts to transfer data from reallocated sectors to a spare area. Both successful & unsuccessful attempts are counted. | |
| 197 | C5 | Current Pending Sector Count | Number of “unstable” sectors (waiting to be remapped). If the unstable sector is subsequently written or read successfully, this value is decreased and the sector is not remapped. Read errors on the sector will not remap the sector, it will only be remapped on a failed write attempt. This can be problematic to test because cached writes will not remap the sector, only direct I/O writes to the disk. | |
| 198 | C6 | Uncorrectable Sector Count | The total number of uncorrectable errors when reading/writing a sector. A rise in the value of this attribute indicates defects of the disk surface and/or problems in the mechanical subsystem. | |
| 199 | C7 | UltraDMA CRC Error Count | The number of errors in data transfer via the interface cable as determined by ICRC (Interface Cyclic Redundancy Check). | |
| 200 | C8 | Write Error Rate / Multi-Zone Error Rate |
The total number of errors when writing a sector. | |
| 201 | C9 | Soft Read Error Rate | Number of off-track errors. If non-zero, make a backup. | |
| 202 | CA | Data Address Mark errors | Number of Data Address Mark errors (or vendor-specific).[citation needed] | |
| 203 | CB | Run Out Cancel | Number of ECC errors | |
| 204 | CC | Soft ECC Correction | Number of errors corrected by software ECC[citation needed] | |
| 205 | CD | Thermal Asperity Rate (TAR) | Number of thermal asperity errors.[citation needed] | |
| 206 | CE | Flying Height | ? | Height of heads above the disk surface.[citation needed] |
| 207 | CF | Spin High Current | ? | Amount of high current used to spin up the drive.[citation needed] |
| 208 | D0 | Spin Buzz | ? | Number of buzz routines to spin up the drive[citation needed] |
| 209 | D1 | Offline Seek Performance | ? | Drive’s seek performance during offline operations[citation needed] |
| 211 | D3 | Vibration During Write | ? | Vibration During Write[citation needed] |
| 212 | D4 | Shock During Write | ? | Shock During Write[citation needed] |
| 220 | DC | Disk Shift | Distance the disk has shifted relative to the spindle (usually due to shock). Unit of measure is unknown. | |
| 221 | DD | G-Sense Error Rate | The number of errors resulting from externally-induced shock & vibration. | |
| 222 | DE | Loaded Hours | ? | Time spent operating under data load (movement of magnetic head armature)[citation needed] |
| 223 | DF | Load/Unload Retry Count | ? | Number of times head changes position.[citation needed] |
| 224 | E0 | Load Friction | Resistance caused by friction in mechanical parts while operating.[citation needed] | |
| 225 | E1 | Load/Unload Cycle Count | Total number of load cycles[citation needed] | |
| 226 | E2 | Load ‘In’-time | ? | Total time of loading on the magnetic heads actuator (time not spent in parking area).[citation needed] |
| 227 | E3 | Torque Amplification Count | Number of attempts to compensate for platter speed variations[citation needed] | |
| 228 | E4 | Power-Off Retract Cycle | The number of times the magnetic armature was retracted automatically as a result of cutting power.[citation needed] | |
| 230 | E6 | GMR Head Amplitude | ? | Amplitude of “thrashing” (distance of repetitive forward/reverse head motion)[citation needed] |
| 231 | E7 | Temperature | Drive Temperature | |
| 240 | F0 | Head Flying Hours | ? | Time while head is positioning[citation needed] |
| 250 | FA | Read Error Retry Rate | Number of errors while reading from a disk | |
| 254 | FE | Free Fall Protection | Number of “Free Fall Events” detected [13] |