Caching operation | Fujitsu MHU2100AT instruction

6.4 Read-ahead Cache

6.4.2 Caching operation

The caching operation is performed only when the commands listed below are received. If any of the following data are stored on the data buffer, the data is sent to the host system.

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All of the sector data that this command processes.

A part of the sector data including the start sector, that this command processes.

If part of the data to be processed is stored on the data buffer, the remaining data is read from disk media and sent to the host system.

(1) Commands that are targets of caching

The commands that are targets of caching are as follows:

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READ SECTOR(s) (EXT)

READ MULTIPLE (EXT)

READ DMA(EXT)

However, if the caching function is prohibited by the SET FEATURES command, the caching operation is not performed.

(2) Data that is a target of caching

The data that is a target of caching are as follows:

1)Read-ahead data that is read from disk media and saved to the data buffer upon completion of execution of a command that is a target of caching.

2)Pre-read data that is read from disk media and saved to the data buffer before execution of a command that is a target of caching.

3)Data required by a command that is a target of caching and has been sent to the host system one. If the sector data requested by the host has not been completely stored in the read cache portion of the buffer, this data does not become a target of caching. Also, If sequential hits occur continuously, the caching-target data required by the host becomes invalid because that data is overwrited by new data.

(3)Invalidating caching-target data

Data that is a target of caching on the data buffer is invalidated under the following conditions:

C141-E202-01EN

6-13

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Fujitsu MHU2100AT manual Caching operation, Commands that are targets of caching, Read Multiple EXT Read Dmaext

Contents

MHU2100AT Disk Drive Product Manual Handling of This Manual For Safe Operation Revision History This page is intentionally left blank Overview of Manual Preface Conventions Conventions for Alert MessagesOperating Environment Liability Exception This page is intentionally left blank Important Alert Messages Important Alert Items This page is intentionally left blank MHU2100AT Disk Drive Product Manual MHU2100AT Disk Drive Maintenance ManualManual Organization This page is intentionally left blank Contents Theory of Device Operation Installation Conditions Interface Contents 100 120 Operations Glossary GL-1 Acronyms and Abbreviations AB-1 Index IN-1 Figures Illustrations Execution example of Read Multiple command Tables Surface temperature measurement points and standard 25 Relationship between combination of Identifier This page is intentionally left blank Device Overview Adaptability FeaturesFunctions and performance Read-ahead cache system Error correction and retry by ECCConnection to ATA interface Data buffer Specifications 1 Device SpecificationsSpecifications summary Examples of model names and product numbers Specifications 2Model and product number MHU2100AT Ripple Power RequirementsInput Voltage Current and power dissipation Environmental specifications Environmental SpecificationsCurrent fluctuation Typ. at +5 V when power is turned on Power on/off sequence Shock and Vibration Acoustic noise specificationShock and vibration specification Acoustic Noise Mean time between failures Mtbf Service lifeData assurance in the event of power failure Reliability Media Defects Error RateUnrecoverable read error Positioning error Advanced Power Management Advanced Power Management Advanced Power Management This page is intentionally left blank Device Configuration Device Configuration Read/write circuit System ConfigurationATA interface 2 1 drive connection 3 2 drives connection 2 drives configuration Installation Conditions Dimensions Dimensions Orientation MountingIntegration Guidance C141-E144 PCA FrameLimitation of mounting Location of breather Ambient temperature Handling cautions Service area Handling cautions Cable Connections Device connector FCI Cable connector specificationsCable connector specifications Device connection Location of setting jumpers Jumper SettingsPower supply connector CN1 Master drive-slave drive setting Factory default setting 14 Csel setting Csel setting 16 Example 2 of Cable Select Power Up in Standby setting Theory of Device Operation Spindle OutlineSubassemblies Disk Spindle motor driver circuit Circuit ConfigurationAir filter Servo circuit Power Supply Configuration PCA Power-on operation sequence Power-on Sequence Self-calibration Self-calibration contents Execution timing of self-calibration Command processing during self-calibration RLL code Meeprml Read/write CircuitRead/write preamplifier PreAMP Write circuit Programmable filter circuit Read circuitAGC circuit Viterbi detection circuit Digital PLL circuitFIR circuit D converter circuit Servo control circuit Servo Control A converter DAC Power amplifierMicroprocessor unit MPU Servo burst capture circuit VCM current sense resistor CSR Spindle motor control circuitDriver circuit Outer guard band Data-surface servo formatInner guard band Data area Physical sector servo configuration on disk surface Servo frame format Track following operation Actuator motor controlOperation to move the head to the reference cylinder Seek operation Spindle motor control Start modeAcceleration mode Stable rotation mode Theory of Device Operation Interface Physical Interface Interface signals Dasp GND Signal assignment on the connectorSignal assignment on the interface connector DA1 PDIAG-, Cblid DA0 DA2 Dior MstrDiow Stop Iordy PdiagCblid Dasp Logical Interface DA2 DA1 DA0 1 I/O registersI/O registers UNC Idnf Command block registersError register X’1F1’ Data register X’1F0’ Sector Count register X’1F2’ Features register X’1F1’SET Multiple Mode Cylinder High register X’1F5’ Sector Number register X’1F3’Cylinder Low register X’1F4’ BSY Device/Head register X’1F6’DEV HS3 HS2 HS1 HS0 Status register X’1F7’ Interface Alternate Status register X’3F6’ Command register X’1F7’Control block registers HOB Srst Host CommandsCommand code and parameters Device Control register X’3F6’ Parameter Used Command code and parameters 1Command Name EXT Flush Cache EXT Command code and parameters 2 Host Commands Command descriptions Host Commands Recalibrate X’10’ to X’1F’ MSB Read Sectors X’20’ or X’21’ End head No. / LBA MSB Read Long X’22’ or X’23’ Write Sectors X’30’ or X’31’ 1F7 HST Status information 1F6 HDH Write Long X’32’ or X’33’ Write Verify X’3C’ Read Verify Sectors X’40’ or X’41’ Seek X’70’ to X’7F’ Diagnostic code Execute Device Diagnostic X’90’ Host Commands Initialize Device Parameters X’91’ Download Micro Code X’92’ Operation of Download Micro Code Standby Immediate X’94’ or X’E0’ Idle Immediate X’95’ or X’E1’ Standby X’96’ or X’E2’ Idle X’97’ or X’E3’ Host Commands ’FF’ Check Power Mode X’98’ or X’E5’ Sleep X’99’ or X’E6’ Smart X’B0 Features Register values subcommands and functions 1 Smart Read LOG Features Register values subcommands and functions 2Smart Enable Operations Smart Disable Operations ’DA’ Smart Return Status Features Register values subcommands and functions 3Smart ENABLE/DISABLE Auto OFF-LINE Interface Format of insurance failure threshold value data Format of device attribute value data1FF Attribute ID Data format version number Raw attribute value Status FlagCurrent attribute value Attribute value for the worst case so far 11 Self-test execution status 10 Off-line data collection statusSelf-test execution status 13 Failure prediction capability flag Off-line data collection capability12 Off-line data collection capability Failure prediction capability flag Insurance failure threshold Error logging capability14 Error logging capability Check sum Smart error logging 16 Data format of Smart Summary Error Log 17 Data format of Smart Comprehensive Error Log Command data structureError data structure Total number of drive errors Self-test number Smart Self-Test18 Smart self-test log data format 1FC Current Span under test 19 Selective self-test log data structureTest Span Current LBA under test Selective Self-test pending time min Feature Flags20 Selective self-test feature flags Device Configuration Identify Device Configuration XB1Device Configuration Restore Device Configuration Freeze Device Configuration SET FR = C3h Device Configuration Restore FR = C0hDevice Configuration Freeze Lock FR = C1h Device Configuration Identify FR = C2h Host Commands 21 Device Configuration Identify data structure Read Multiple X’C4’ Execution example of Read Multiple command MSB Write Multiple X’C5’ Interface SET Multiple Mode X’C6’ Interface Read DMA X’C8’ or X’C9’ End head No. / LBA MSB Write DMA X’CA’ or X’CB’ Interface Read Buffer X’E4’ Flush Cache X’E7’ Write Buffer X’E8’ Identify Device X’EC’ Identify Device DMA X’EE’ ’3FFF’ 22 Information to be read by Identify Device command 1 22 Information to be read by Identify Device command 2 Word Command without interrupt supports 2, 4, 8 and 16 sectors = Supports the Host Protected Area feature set = Supports the CFA Compact Flash Association feature set Interface Host Commands Diagnosis Word Bit Reserved Security level High, 1 Maximum ’BB’ SET Features X’EF’23 Features register values and settable modes ’AA’ Data Transfer Mode Advanced Power Management APM Automatic Acoustic Management AAM 24 Contents of Security SET Password data At command issuance I-O register contents 1F7 hCM 1F6 hDH Security UNLOCKX’F2’ When the master password is selectedWhen the user password is selected Host Commands Security Erase Prepare X’F3’ Security Erase Unit X’F4’ Security Freeze Lock X’F5’ At command issuance I-O register contents 1F7 hCM 1F6 hDH 26 Contents of security password Host Commands Read Native MAX Address X’F8’ SET MAX Address SET MAX X’F9’ SET MAX SET Password FR = 01h SET MAX Lock FR = 02h SET MAX Unlock FR = 03h SET MAX Freeze Lock FR = 04h Interface Read Sectors EXT X’24’ Option customizing Description Read DMA EXT X’25’ Option customizing Description HOB=1 Error reporting conditionsHOB=0 Read Multiple EXT X’29’ Option customizing Description Read LOG EXT X2F Optional command Customize Description Interface Write Sectors EXT X’34’ Option customizing Description Write DMA EXT X’35’ Option customizing Description SET MAX Address EXT X’37’ Option customizing Description SET MAX LBA Write Multiple EXT X’39’ Option customizing Description Write LOG EXT X’3F’ Optional command Customize Description Host Commands Read Verify Sectors EXT X’42 Option customizing Description Flush Cache EXT X’EA’ Option customizing Description 27 Command code and parameters 1 Error posting 27 Command code and parameters 2 Execute Device Diagnostic Initialize Device Parameters Command ProtocolPIO Data transferring commands from device to host Read Sectors Command protocol Protocol for command abort PIO Data transferring commands from host to device Write Sectors command protocol Commands without data transfer Read DMA EXT Write DMA EXT Indentify Device DMA Other commandsDMA data transfer commands Read Multiple EXT Write Multiple EXT Sleep Normal DMA data transfer Overview Ultra DMA Feature Set Initiating an Ultra DMA data in burst Phases of operationUltra DMA data in commands Data in transfer Pausing an Ultra DMA data in burst Terminating an Ultra DMA data in burst Interface Ultra DMA Feature Set Initiating an Ultra DMA data out burst Ultra DMA data out commands Data out transfer Pausing an Ultra DMA data out burst Terminating an Ultra DMA data out burst Ultra DMA Feature Set Ultra DMA CRC rules DIOW-STOP Series termination required for Ultra DMA28 Recommended series termination for Ultra DMA DIOR-HDMARDY-HSTROBE PIO data transfer timing TimingPIO data transfer Multiword data transfer 10 Multiword DMA data transfer timing mode 11 Initiating an Ultra DMA data in burst Ultra DMA data transfer Strobe Name Mode Comment MIN MAX 29 Ultra DMA data burst timing requirements 2 30 Ultra DMA sender and recipient timing requirements Mode Name Comment DD150 at host Sustained Ultra DMA data in burstDstrobe at device DD150 at device Dstrobe at host Stop Host pausing an Ultra DMA data in burstDmarq Dmack Device terminating an Ultra DMA data in burst DA0, DA1, DA2 CS0, CS1 Host terminating an Ultra DMA data in burstHost 16 Initiating an Ultra DMA data out burst Hstrobe at device DD150 at device Sustained Ultra DMA data out burstHstrobe at host DD150 at host Hstrobe host DD150 Host Device pausing an Ultra DMA data out burstDevice DMACK- host Stop host DDMARDY- device 19 Host terminating an Ultra DMA data out burst Host terminating an Ultra DMA data out burst DD150 Host Device terminating an Ultra DMA data out burstDmarq device DMACK- host Only master device is present Power-on and resetMaster and slave devices are present 2-drives configuration This page is intentionally left blank Operations Response to power-on Device Response to the Reset Response to power-on Response to hardware reset Response to hardware reset Response to software reset Response to software reset Response to diagnostic command Response to diagnostic command Active idle mode Power SavePower save mode Active mode Sleep mode Standby mode Spare area Power commandsDefect Processing Track slip processing Alternating processing for defective sectorsSector slip processing Automatic alternating processing Automatic alternating processing Read Sectors EXT Read Multiple EXT Read DMA EXT Read-ahead CacheData buffer structure 8MB buffer 8,388,608 bytes Data that is a target of caching Commands that are targets of cachingCaching operation Read Multiple EXT Read Dmaext Operations Miss-hit Using the read segment buffer Sequential Hit Full hit Partial hit Invalidation of cached data Command that are targets of cachingWrite Cache Cache operation Enabling and disabling Status report in the event of an errorReset response Cashing function when power supply is turned on Write Cache This page is intentionally left blank Glossary Positioning Power save modeRotational delay PIO Programmed input-output VCM Status This page is intentionally left blank Acronyms and Abbreviations This page is intentionally left blank AAM Index Index Information to be read by Identify Read Native MAX Address Read Sectors Command Surface temperature measurement This page is intentionally left blank Japan Comment Form This page is intentionally left blank C141-E202-01EN This page is intentionally left blank