Full hit | Fujitsu MHU2100AT manual

6.4 Read-ahead Cache

6.4.3.3 Full hit

In this situation, all read requested data is stored in the data buffer. Transfer of the read requested data is started from the location where hit data is stored. For data that is a target of caching and remains before a full hit, the data is retained when execution of the command is completed. This is done so that a new read- ahead operation is not performed. If the full hit command is received during the read-ahead operation, a transfer of the read requested data starts while the read- ahead operation is in progress.

1)An example is the state shown below where the previous read command is executing sequential reading. First, HAP is set at the location where hit data is stored.

	HAP end location of the previous read command
HAP	HAP (It is reset to the hit data location for transfers.)

Cache data

Full hit data

Cache data

DAP

DAP end location of the previous read command

2)The read requested data is transferred, and a new read-ahead operation is not performed.

HAP (stop)

Cache data

Full hit data

Cache data

C141-E202-01EN

6-17

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Fujitsu MHU2100AT manual Full hit

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 for Alert Messages Operating EnvironmentConventions Liability Exception This page is intentionally left blank Important Alert Messages Important Alert Items This page is intentionally left blank MHU2100AT Disk Drive Maintenance Manual Manual OrganizationMHU2100AT Disk Drive Product Manual 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 Features Functions and performanceAdaptability Read-ahead cache system Error correction and retry by ECCConnection to ATA interface Data buffer Device Specifications Specifications summarySpecifications 1 Examples of model names and product numbers Specifications 2Model and product number MHU2100AT Power Requirements Input VoltageRipple 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 Mounting Integration Guidance C141-E144Orientation Frame Limitation of mountingPCA Location of breather Ambient temperature Handling cautions Service area Handling cautions Cable Connections Device connector FCI Cable connector specificationsCable connector specifications Device connection Jumper Settings Power supply connector CN1Location of setting jumpers 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 Read circuit AGC circuitProgrammable filter 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 Spindle motor control circuit Driver circuitVCM current sense resistor CSR 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 1 I/O registers I/O registersDA2 DA1 DA0 UNC Idnf Command block registersError register X’1F1’ Data register X’1F0’ Features register X’1F1’ SET Multiple ModeSector Count register X’1F2’ Sector Number register X’1F3’ Cylinder Low register X’1F4’Cylinder High register X’1F5’ BSY Device/Head register X’1F6’DEV HS3 HS2 HS1 HS0 Status register X’1F7’ Interface Command register X’1F7’ Control block registersAlternate Status register X’3F6’ HOB Srst Host CommandsCommand code and parameters Device Control register X’3F6’ Command code and parameters 1 Command NameParameter Used 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 Features Register values subcommands and functions 3 Smart ENABLE/DISABLE Auto OFF-LINE’DA’ Smart Return Status Interface Format of device attribute value data 1FFFormat of insurance failure threshold value data Attribute ID Data format version number Raw attribute value Status FlagCurrent attribute value Attribute value for the worst case so far 10 Off-line data collection status Self-test execution status11 Self-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 Feature Flags 20 Selective self-test feature flagsSelective Self-test pending time min 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 When the master password is selected When the user password is selectedSecurity UNLOCKX’F2’ 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 Error reporting conditions HOB=0HOB=1 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 Command Protocol PIO Data transferring commands from device to hostExecute Device Diagnostic Initialize Device Parameters 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 Phases of operation Ultra DMA data in commandsInitiating an Ultra DMA data in burst 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 Timing PIO data transferPIO data transfer timing 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 Host terminating an Ultra DMA data in burst HostDA0, DA1, DA2 CS0, CS1 16 Initiating an Ultra DMA data out burst Sustained Ultra DMA data out burst Hstrobe at host DD150 at hostHstrobe at device DD150 at device Device pausing an Ultra DMA data out burst Device DMACK- host Stop host DDMARDY- deviceHstrobe host DD150 Host 19 Host terminating an Ultra DMA data out burst Host terminating an Ultra DMA data out burst Device terminating an Ultra DMA data out burst Dmarq device DMACK- hostDD150 Host Power-on and reset Master and slave devices are present 2-drives configurationOnly master device is present 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 Power commands Defect ProcessingSpare area Alternating processing for defective sectors Sector slip processingTrack 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