Seagate ST31000640SSIM 4 S.M.A.R.T, Controlling S.M.A.R.T, Performance impact, Reporting control

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5.2.4S.M.A.R.T.

S.M.A.R.T. is an acronym for Self-Monitoring Analysis and Reporting Technology. This technology is intended to recognize conditions that indicate imminent drive failure and is designed to provide sufficient warning of a failure to allow you to back up the data before an actual failure occurs.

Note. The drive’s firmware monitors specific attributes for degradation over time but can’t predict instanta- neous drive failures.

Each monitored attribute has been selected to monitor a specific set of failure conditions in the operating per- formance of the drive and the thresholds are optimized to minimize “false” and “failed” predictions.

Controlling S.M.A.R.T.

The operating mode of S.M.A.R.T. is controlled by the DEXCPT and PERF bits on the Informational Exceptions Control mode page (1Ch). Use the DEXCPT bit to enable or disable the S.M.A.R.T. feature. Setting the DEX- CPT bit disables all S.M.A.R.T. functions. When enabled, S.M.A.R.T. collects on-line data as the drive performs normal read and write operations. When the PERF bit is set, the drive is considered to be in “On-line Mode Only” and will not perform off-line functions.

You can measure off-line attributes and force the drive to save the data by using the Rezero Unit command. Forcing S.M.A.R.T. resets the timer so that the next scheduled interrupt is in two hours.

You can interrogate the drive through the host to determine the time remaining before the next scheduled mea- surement and data logging process occurs. To accomplish this, issue a Log Sense command to log page 0x3E. This allows you to control when S.M.A.R.T. interruptions occur. Forcing S.M.A.R.T. with the RTZ command resets the timer.

Performance impact

S.M.A.R.T. attribute data is saved to the disk so that the events that caused a predictive failure can be recre- ated. The drive measures and saves parameters once every two hours subject to an idle period on the drive interfaces. The process of measuring off-line attribute data and saving data to the disk is uninterruptable. The maximum on-line only processing delay is summarized below:

Maximum processing delay

 

 

On-line only delay

Fully-enabled delay

 

DEXCPT = 0, PERF = 1

DEXCPT = 0, PERF = 0

S.M.A.R.T. delay times

42 milliseconds

163 milliseconds

5.2.5Reporting control

Reporting is controlled by the MRIE bits in the Informational Exceptions Control mode page (1Ch). Subject to the reporting method, the firmware will issue to the host an 01-5Dxx sense code. The error code is preserved through bus resets and power cycles.

Determining rate

S.M.A.R.T. monitors the rate at which errors occur and signals a predictive failure if the rate of degraded errors increases to an unacceptable level. To determine rate, error events are logged and compared to the number of total operations for a given attribute. The interval defines the number of operations over which to measure the rate. The counter that keeps track of the current number of operations is referred to as the Interval Counter.

S.M.A.R.T. measures error rates. All errors for each monitored attribute are recorded. A counter keeps track of the number of errors for the current interval. This counter is referred to as the Failure Counter.

Barracuda ES.2 SAS Product Manual, Rev. G

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Contents ST31000640SS ST3750630SS ST3500620SS Barracuda ES.2 SASPage General description Performance characteristicsReliability specifications Physical/electrical specificationsInterface requirements Defect and error managementInstallation Seagate Technology Support Services Barracuda ES.2 SAS Product Manual, Rev Scope Barracuda ES.2 SAS Product Manual, Rev. G Electromagnetic susceptibility Standards, compliance and reference documentsStandards Electromagnetic compatibilityCompliance Reference documents Barracuda ES.2 SAS Product Manual, Rev. G Barracuda ES.2 drive illustration General descriptionReliability Standard featuresMedia description PerformanceProgrammable drive capacity Factory-installed optionsFormatted capacities Barracuda ES.2 SAS Product Manual, Rev. G Seek performance Performance characteristicsInternal drive characteristics Access timeStart/stop time Format command execution time minutesGeneral performance characteristics Caching write data Prefetch/multi-segmented cache controlCache operation Prefetch operation Unrecoverable Errors Reliability specificationsError rates Recoverable ErrorsPreventive maintenance Reliability and serviceSeek errors Interface errorsReporting control 4 S.M.A.R.TControlling S.M.A.R.T Performance impactThermal monitor Temperature Log Page 0DhPredictive failures Invoking DST State of the drive prior to testingDST failure definition ImplementationLog page entries Product warrantyShort test Function Code 001b Extended test Function Code 010bProduct repair and return information ShippingBarracuda ES.2 SAS Product Manual, Rev. G ST31000640SS DC power requirements Physical/electrical specificationsAC power requirements DC power requirementsST3500620SS DC power requirements ST3750630SS DC power requirementsCurrent profiles General DC power requirement notesPower sequencing Conducted noise immunityTypical ST31000640SS drive +5V and +12V current profiles Typical ST3500620SS drive +5V and +12V current profiles Power dissipationBarracuda ES.2 SAS Product Manual, Rev. G Environmental limits Temperature a. OperatingShock Relative humidityEffective altitude sea level a. Operating Shock and vibrationPackage size Packaged/product weight Drop height Corrosive environment Air cleanlinessVibration a. Operating-normal AcousticsSee Section Barracuda ES.2 SAS Product Manual, Rev. G Physical dimensions Mechanical specificationsDrive error recovery procedures Defect and error managementDrive internal defects/errors 108.29 Media Pre-Scan SAS system errorsBackground Media Scan Idle Read After Write Deferred Auto-ReallocationDrive orientation InstallationAir flow CoolingGrounding Drive mountingBarracuda ES.2 SAS Product Manual, Rev. G Interface requirements SAS featuresDual port support Command name Command code Supported Scsi commands supportedCommands supported by Barracuda ES.2 SAS family drives Commands supported by Barracuda ES.2 SAS family drives Commands supported by Barracuda ES.2 SAS family drives Commands supported by Barracuda ES.2 SAS family drives Barracuda ES.2 SAS inquiry data Bytes Data hex Mode Sense dataInquiry data Page Mode Pages 2.1 ST31000640SS Mode Sense data2.2 ST3750630SS Mode Sense data 2.3 ST3500620SS Mode Sense data Miscellaneous status Miscellaneous operating features and conditionsMiscellaneous features Supported Feature or conditionSAS physical interface Datum B Connector requirements Physical characteristicsSAS pin descriptions Pin Signal name Signal typeElectrical description Pin descriptionsReady LED Out Signal characteristicsPower SAS transmitters and receiversEye masks Eye masks overview LED drive signalDifferential signals General interface characteristicsNormalized time in UI Receive eye maskJitter tolerance masks Absolute amplitudeFrequency in kHz Peak-toSinusoidal JitterSignal characteristica Units Gbps Transmitter signal characteristicsGbps m, n Deterministic jitterq Receiver signal characteristicsSignal characteristic Units Gbps Maximum allowable jitterImpedance requirements Sheet 1 Impedance specificationsReceiver jitter tolerance Compliant jitter test pattern CjtpatElectrical TxRx connections Transmitter characteristicsImpedance requirements Sheet 2 = -5,437dB Shows the zero-length test load Receiver characteristics Barracuda ES.2 SAS Product Manual, Rev. G
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