Active@ Hard Disk Monitor

Active@ Hard Disk Monitor

S.M.A.R.T. Information

Self-Monitoring, Analysis and Reporting Technology, or S.M.A.R.T. is a monitoring system for computer hard disks to detect and report on various indicators of reliability and assist in the anticipation of failures.

S.M.A.R.T. Attributes

Each hard disk drive manufacturer defines a set of attributes and selects threshold values which attributes should not go below under normal operation. Attribute values can range from 1 to 253 (1 representing the worst case and 253 representing the best).

Depending on the HDD manufacturer, a value of 100 or 200 will often be chosen as the "normal" value. Manufacturers that have supported one or more S.M.A.R.T. attributes in various products include: Samsung, Seagate, IBM ( Hitachi), Fujitsu, Maxtor, Western Digital.

These manufacturers do not necessarily agree on precise attribute definitions and measurement units; therefore the following list should be regarded as a general reference only. Note that the attribute values are always mapped to the range of 1 to 253 in a way that means higher values are better.

For example, the "Reallocated Sectors Count" attribute 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.

Known S.M.A.R.T. attributes

Key: Higher is better Lower is better
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. Any number indicates a problem with either disk surface or read/write heads.
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).
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, the more sectors that are reallocated, the more read/write speed will decrease.
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 failure in the mechanical positioning system, a servo damage or a thermal widening of the hard disk, seek errors arise. More seek errors indicates a worsening condition of a disk surface and the mechanical subsystem.
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.
190 BE Airflow Temperature (WDC) Airflow temperature on Western Digital HDs (Same as temp. (C2), but current value is 50 less.)
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 ST910021AS: Verified Present
Seagate ST3802110A: Verified Present 2007-02-13
Seagate ST980825AS: Verified Present 2007-04-05
Seagate ST3320620AS: Verified Present 2007-04-23
Seagate ST3500641AS: Verified Present 2007-06-12
Seagate ST3250824AS: Verified Present 2007-08-07
191 BF G-sense error rate Frequency of mistakes as a result of impact loads
192 C0 Power-off Retract Count   Number of times the heads are loaded off the media. Heads can be unloaded without actually powering off. (or Emergency Retract Cycle count -Fujitsu)
193 C1 Load/Unload Cycle   Count of load/unload cycles into head landing zone position.
194 C2 Temperature Current internal temperature.
195 C3 Hardware ECC Recovered Time between ECC-corrected errors.
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).
203 CB Run Out Cancel Number of ECC errors
204 CC Soft ECC Correction Number of errors corrected by software ECC
205 CD Thermal Asperity Rate (TAR) Number of thermal asperity errors.
206 CE Flying Height    
207 CF Spin High Current   Amount of high current used to spin up the drive.
208 D0 Spin Buzz   Number of buzz routines to spin up the drive
209 D1 Offline Seek Performance   Drive’s seek performance during offline operations
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)
223 DF Load/Unload Retry Count   Number of times head changes position.
224 E0 Load Friction Resistance caused by friction in mechanical parts while operating.
225 E1 Load/Unload Cycle Count Total number of load cycles
226 E2 Load 'In'-time   Total time of loading on the magnetic heads actuator (time not spent in parking area).
227 E3 Torque Amplification Count Number of attempts to compensate for platter speed variations
228 E4 Power-Off Retract Cycle The number of times the magnetic armature was retracted automatically as a result of cutting power.
230 E6 GMR Head Amplitude   Amplitude of "thrashing" (distance of repetitive
forward/reverse head motion)
231 E7 Temperature   Drive Temperature
240 F0 Head Flying Hours Time while head is positioning
250 FA Read Error Retry Rate Number of errors while reading from a disk

Learn more: