Data Buffer | Fujitsu MBC2073RC, MBC2036RC, MBA3300RC, MBA3147RC

CHAPTER 3 Data Buffer Management

3.1Data Buffer

3.2Look-Ahead Cache Feature

In this chapter, the configuration of the data buffer with which the HDD is equipped, its operation and the operation of the cache feature are described.

3.1 Data Buffer

3.1.1 Data buffer configuration and basic operation

The HDD is equipped with a data buffer, which makes it possible to efficiently execute data transfer operations between INIT (initiator) and a disk drive.

The HDD divides data buffer into Pages, which are minimum allocation size for Cache. Actually two or more Pages are linked and a Cache Segment is constructed per the requested data size from INIT. Since HDD automatically controls the best suitable Cache Segment, INIT cannot be changed neither the Page size nor the Segment size.

Each data buffer is a 2 ports of FIFO (First-In First-Out) ring buffer, with one port allocated for transfers with the disk media and the other port for data transfers with the interface (INIT). Mutual ports operate asynchronously and since it is possible to efficiently absorb variations in data transfer speed between the ports, the INIT can perform data transfer operations with the HDD while being virtually unaware of differences between the interface data transfer rate and the disk drive data transfer rate.

Even if the data transfer capacity of the interface (INIT) is lower than the disk drive's data transfer rate, the data buffer can perform data transfers to the system under optimum conditions without using sector interleave. Also, if the data transfer capacity of the interface (INIT) is higher than the disk drive's data transfer rate, it is possible to minimize the occupancy time on the interface by accumulating an appropriate amount of data in the data buffer.

Only one cache segment of the divided data buffer is used by one command and the data in the other cache segments are held.

Figure 3.1 shows the data buffer image.

C141-C013

127

Image 131

Fujitsu MBC2073RC, MBC2036RC, MBA3300RC, MBA3147RC, MBA3073RC Data Buffer, Data buffer configuration and basic operation

Contents

C141-C013-01EN Handling of This Manual For Safe Operation Revision History This page is intentionally left blank Overview of Manual Acronyms and Abbreviations Sense Data and Error Recovery MethodsDisk Media Management Glossary Conventions Used in this Manual Conventions for Alert Messages Manual Organization Ansi Referenced Standards Contents Contents Command Processing 103 135 Command SpecificationsData Buffer Management 127 Parameter Data Format 281 359 Sense Data and Error Recovery Methods 384 Termination status analysis and error recovery methods374 382 Glossary 417 Acronyms and Abbreviations 419 Index 421 Tables Figures 100 107 226 311 Total unrecoverable verify errors posted to Init SAS Interface SAS Interface Topologies in SAS Interface Topologies in SAS Interface SAS Layering Ports narrow ports and wide ports Physical links and phys Ports narrow ports and wide ports SAS devices SAS devices Example of potential pathways Pathways Connections SAS address format Names and identifiersSAS addresses Names and identifiers Hashed SAS address code parameter Hashed SAS address Usage of special characters Phy layer1 8b10b coding Phy layer Reset-related terminology Link reset sequence OOB signal timing specifications Start conditions of the link reset sequenceOut of band OOB signals Comsas OOB signal transmitter requirementsCOMINIT/RESET OOB signal receiver negation time detection requirements OOB signal receiver burst time detection requirementsCOMINIT/COMRESET OOB signal receiver idle time detection requirements 3 4 n SAS OOB sequency Scenario 3 SAS phy B misses SAS phy As Cominit Scenario 2 SAS phy a starts SAS OOB sequence Exception handling in the OOB sequence ∙ When the Cominit signal cannot be detected∙ When the Comsas signal cannot be detected SAS speed negotiation sequence 11 SAS speed negotiation window SAS speed negotiation sequence timing specifications SAS Interface 12 SAS speed negotiation sequence Example 14 Phy reset sequence Example Phy reset sequence after devices are attached Exception handling in the speed negotiation sequence When the speed negotiation sequence is successfulPhy layer dword synchronization DWS 10 Primitives not specific to type of connection 1/2 Link layerPrimitives 10 Primitives not specific to type of connection 2/2 Link layer 11 Primitives used only inside SSP and SMP connections AIP Arbitration in progress Primitive sequencesPrimitives not specific to type of connections 12 Primitive sequences Broadcast Break Eoaf End of address frame ErrorHardreset Close Openreject NotifyOpenaccept Supported 13 Openreject abandon primitives No Destination 14 Openreject retry primitives Soaf Start of address frame Done Primitives used only inside SSP and SMP connectionsACK acknowledge 15 Done primitives SOF Start of frame EOF End of frameNAK negative acknowledgement Rrdy 16 Clock skew management Align insertion requirement Clock skew managementIdle physical link 17 Scrambling for different data dword types Scrambling 18 Address frame format Address framesAddress frames overview Address frames 20 Device Type field Identify address frame19 Identify address frame format PHY Identifier Device TypeSAS Address SMP Open address frame21 Open address frame format 22 Protocol field 23 Connection Rate field ∙ Initiator Connection TAG 24 Arbitration Wait Time field∙ Connection Rate ∙ Arbitration Wait Time Identification and hard reset sequence∙ Destination SAS Address ∙ Pathway Blocked Count Connection request Connections overview Arbitration fairness Connection responses25 Connection responses Bits 79-64 79 is MSB Bits 63-0 0 is LSB 27 Abort connection responses Aborting a connection request Close Closing a connection28 Close connection responses Rate matching Breaking a connection29 Break connection responses 30 Rate matching Align and/or Notify insertion requirements SSP link layer Interlocked frames SSP frame transmission and receptionSSP flow control Creditblocked 31 SSP frame interlock requirements 17 Interlocked frames 18 Non-interlocked frames with the same tag 20 Closing an SSP connection example 32 SSP frame format Transport layerSSP frame format Responsedata Transport layer33 Frame Type field Nodata SAS Interface Information units Command information unit34 Command information unit Ordered 35 Task Attribute fieldSimple Head of Queue Transport layer 36 Task information unit Task information unit Abort Task SET 37 Task Management Function field 38 Xferrdy information unit Response DataXferrdy information unit Requested Offset Write Data 39 An example of requested offset 21 Example of Xferrdy frames Length 40 Data information unit Data information unit SAS Interface TOO Much Write Data 42 Datapres field Response information unit41 Response information unit ∙ Response information unit Responsedata format ∙ Response information unit Nodata format ∙ Response information unit Sensedata format 43 Response Data field44 Response Code field Transport layer 22 Example of Task frame Sequences of SSP frames 23 Example of write command Exceptional event processing of a drive Transport layer Clear Task SET Management Function Complete 45 Exceptional event processing of a drive 1/2 45 Exceptional event processing of a drive 2/2 102 C141-C013 Command Format Command Processing 10-Byte CDB basic format Command Processing6-Byte CDB basic format Operation code Bit Byte Operation CodeControl Byte Operation code Transfer data length Logical block address Handling an illegal CDB Command FormatControl byte Control byte Check Condition status Status ByteStatus Good status Intermediate status Command Terminated statusCondition MET Status Busy status READ, Read EXTENDED, WRITE, Write Extended Command Queuing Function Generation of the Unit Attention condition When a Power On or Reset occursWhen I-T Nexus Loss occurs Unit Attention Condition Logical Unit Reset Commands cleared by another Init Sense Data Hold State Inquiry commandRequest Sense command Report Luns command ∙ ActiveWait state Power Condition LED Display ∙ Commands that can be executed even in the Not Ready state∙ Operation when formatting is not completed normally LED Display LED display Command Processing ExceptionsOverlapped tag Command Processing Exceptions Illegal LUN specification Reserved operation code Error recovery processingRecovery procedures for disk drive errors Outline of disk drive error recovery processing ∙ Nexus Abort processingComparison between SAS and Scsi about definition ∙ Abort processing during write operation Hard Reset 10 Reset processing during write Data Block Addressing Fatal hardware errorsSelf-diagnostic errors Unrecoverable hardware errors Data Block Addressing Data space configuration User space logical block addresses Logical block addressing Alternate area Data Buffer Data buffer configuration and basic operation Read operation Data Buffer Management Write operation Data Buffer Read Read Extended Look-Ahead Cache FeatureCaching object commands Caching operation − Write − Write Extended − Write and Verify Look-Ahead Cache FeatureDisabling caching data Data Buffer Management Caching parameters Look-Ahead operation, Look-Ahead volume This page is intentionally left blank Test Unit Ready Control/Sense Commands Inquiry Command Specifications Control/Sense Commands Fujitsu Standard Inquiry data Version field Command Specifications Command queuing OX0B, Oxfc SAS Version descriptorByte SAM2 Command support data Support VPD information VPD identifier list VPD information VPD information device serial No MSB 10 VPD information device unique information 1/2PIV MBS 10 VPD information device unique information 2/2 Code SET Command Specifications Read Capacity 11 Read Capacity data Mode Select Command Specifications Mode Select parameter structure Command Specifications 12 Mode Select command Group 0 parameter configuration 1/2 SPF 12 Mode Select command Group 0 parameter configuration 2/2 Control/Sense Commands Command Specifications 13 Mode Select parameters Command Specifications Mode Select Extended Byte Sub Page Descriptor Bit Byte Mode Sense 1A 15 Mode 16 Mode Sense data type specifications Control/Sense Commands 17 Mode Sense command group 0 parameter configuration 1/2 Header 17 Mode Sense command group 0 parameter configuration 2/2 Descriptor Block descriptor Control/Sense Commands Mode Sense Extended 5A Header Bit Byte 176 C141-C013 Rezero Unit START/STOP Unit 1B Control/Sense Commands Logical unit reserve function Reserve Reserve right and third party reserve function Reserve Extended Release object and third party release function ReleaseRelease function Release Extended Request Sense Command Specifications LOG Select 4C 19 PC page control 20 LOG Select command parameter configuration Length Code21 Page code Byte 22 Log parameterTSD ETC TMC Parameter code Lbin LOG Sense 4D Log parameters 23 Page Code assignment for the log pages Persistent Reserve in 5E Read Reservation Persistent Reserve in service actions24 Persistent Reserve in service actions Read Keys LSB MSB Persistent Reserve in parameter data for Read Keys25 Persistent Reserve in parameter data for Read Keys Persistent Reserve in parameter data for Read Reservations Format of the Reservation descriptors is defined in Table ∙ Persistent reservations type ∙ Persistent reservations scope28 Persistent reservations scope 29 Persistent reservations type codes Persistent Reserve OUT 5F Command Specifications 30 Persistent Reserve OUT service action codes Persistent Reserve OUT service actions Aptpl Persistent Reserve OUT parameter list31 Persistent Reserve OUT parameter list Control/Sense Commands Command Specifications Persistent Reserve Report Luns A0 33 Report Luns parameter data Report Device Identifier A3 34 Report Device Identifier parameter data SET Device Identifier A4 35 SET Device Identifier parameter data Read Data Access CommandsData Access Commands Command Specifications FUA Read Extended Write 0A Data Access Commands Write Extended 2A Write and Verify 2E Verify 2F Seek 0B Seek Extended 2B Synchronize Cache Format Unit Format Commands Defect list Format Commands 36 Defect list format Specifying the initialization method Stpf 37 Format Unit command parameter list configurationFormat parameters FOV Command Specifications Format Commands 38 Defect descriptor byte distance from index format 39 Defect descriptor physical sector address format Command Specifications Defect processing during initialization 40 Format Unit command defect processing 1/2 40 Format Unit command defect processing 2/2 Bit Byte X07 Reassign Blocks 41 Reassign Block command defect data list configuration = Hardware Error Correction of the defect descriptor 42 Defect data type Bit Byte X37 PList GListTransfer Byte Length MSB Transfer Byte Length LSB 43 Defect data format 44 Read Defect Data command defect data configuration Defect descriptor list 45 Defect data conditions Format Commands Read Defect Data B7 46 Read Defect Data command B7 defect data configuration Self-diagnosis test Maintenance, Diagnostic Commands 47 Self-diagnosis test PER DTE Parameter specification Maintenance, Diagnostic Commands PHY Test 49 Send Diagnostic command parameter list configuration50 Page code 51 Send Diagnostic parameters page code list 52 Send Diagnostic parameters PHY Test function Maintenance, Diagnostic Commands Command Specifications 54 Specifying address format Logical unit Self-Test 55 SELF-TEST Receive Diagnostic Results 1C Parameters 57 Receive Diagnostic Results response data page code list Code list Logical/physical address conversion 59 Address format Write Buffer 3B 60 Write Buffer transfer mode Mode = 0, 0, 0, 1 Header + data, with address specification 61 Write Buffer command buffer data mode = 000 Mode = 0, 1, 0, 1 Microcode download, with saving Mode = 0, 0, 1, 0 Data only, with address specificationMode = 0, 1, 0, 0 Microcode download, without saving Maintenance, Diagnostic Commands Command Specifications Mode = 1, 0, 1, 0 Echo buffer Read Buffer 3C 62 Read Buffer transfer mode 63 Read Buffer command buffer data mode = 0000 Mode = 0, 0, 0, 1 Header + data, with address specification 64 Read Buffer command buffer descriptor Mode = 0, 0, 1, 1 Buffer descriptor Ebos Mode = 1, 0, 1, 1 Echo buffer descriptor65 Read Buffer command echo buffer descriptor Read Long 3E 05 = Illegal Request Write Long 3F Command Specifications Write Same Command Specifications Parameter Data Format Mode Parameters Parameter Data Format Read/Write Error Recovery Parameters Page Code =Mode Select parameters read/write error recovery parameters Write Extended Write Long Write Same Mode ParametersRead Read Extended Read Long Parameter Data Format Mode Parameters EER PER DTE DCR Combinations of error recovery flags Disconnect/Reconnect Parameters Page Code = Mode Select parameters disconnect/reconnect parameters Parameter Data Format Format Parameters Page Code = Mode Select parameters format parameters Parameter Data Format Mode Parameters Parameter Data Format C141-C013 293 Drive Parameters Page Code = Mode Select parameters drive parameters Mode Parameters Verify Verify Error Recovery Parameters Page Code =Mode Select parameters verify error recovery parameters Mode Parameters Caching Parameters Page Code = Mode Select parameters caching parameters Mode Parameters Parameter Data Format Mode Parameters Parameter Data Format Mode Parameters Mode Select parameters control mode parameters Control Mode Parameters Page Code = 0A Mode Parameters TAS task aborted status not supported Mode Parameters Notch Parameters Page Code = 0C 10 Mode Select parameters notch parameters Mode Parameters Port Control Parameter Page Code = 11 Port control parameter Page 0 Format Short Page Format Number of Phys Code Description12 Port control parameter Sub Page Format Long Format This page cannot be modified 13 SAS phy mode descriptor format Parameter Data Format C141-C013 315 14 Power condition parameter Page 0 Format Short Page Format Power Condition Parameter Page Code = 1A Informational Exceptions Control Page Page Code = 1C 15 Mode Select parameters informational exception control Parameter Data Format Mode Parameters 16 Mrie 1/2 16 Mrie 2/2 17 Interval timer Ffff Background Control Mode Parameter Page Code = 1C/subpage =18 Mode Select parameters background control mode parameter Pre-Scan is disabled Parameter Data Format Fujitsu unique parameter Additional Error Recovery Parameters Page Code = 9A 0A 00 00 FF FF FF FF FF FF FF FF 20 Mode parameter default values 21 Log parameter format Log ParametersLog Parameters Parameter Data Format 22 Support log Support Log ETC TMC Buffer Overrun/Underrun23 Buffer overrun/underrun 24 Write error count Write Error Count Write errors recovered with possible delays page 02, code Write errors recovered without delays page 02, code25 Write errors recovered without delays page 02, code TSD ETC Total write errors posted page 02, code27 Total write errors posted page 02, code Total recoverable write errors posted to Init page 02, code 29 Total write bytes processed page 02, code Total write bytes processed page 02, code 32 Read errors recovered without delays page 03, code Read Error Count31 Read error count Read errors recovered without delays page 03, code 34 Total read errors posted page 03, code Read errors recovered with possible delays page 03, code33 Read errors recovered with possible delays page 03, code Total read errors posted page 03, code 36 Total read bytes processed page 03, code Total recoverable read errors posted to Init page 03, codeTotal read bytes processed page 03, code 38 Verify error count Verify Error Count TSD ETC TMC Lbin Verify errors recovered without delays page 05, code39 Verify errors recovered without delays page 05, code Verify errors recovered with possible delays page 05, code 41 Total verify errors posted page 05, code Total verify errors posted page 05, code 43 Total verify bytes processed page 05, code Total verify bytes processed page 05, code 46 Temperature page X0D Non-Medium Error CountTemperature Page X0D 45 Non-medium error count 48 Reference temperature page 0D, code Temperature page 0D, code47 Temperature page 0D, code Reference temperature page 0D, code 50 Date of manufacture page 0E, code Start-Stop Cycle Counter Page X0E49 Start-stop cycle counter page X0E Date of manufacture page 0E, code 52 Specified cycle count over device lifetime page 0E, code Accounting date page 0E, code51 Accounting date page 0E, code Specified cycle count over device lifetime page 0E, code 53 Start-stop cycle counter page 0E, code Start-stop cycle counter page 0E, code 54 Application client page X0F Application Client Page X0F 57 Self-test result parameter data page 10, code Self-Test Result56 Self-test result Self-test result parameter data page 10, code 58 Self-test results values 60 Background medium scan status parameter Background Medium Scan59 Background medium scan 61 BMS status 63 Reassign status 62 Background medium scan parameterMSB LBA LSB 64 Protocol specific port log page format Protocol Specific Port Log Init Details of the log parameter65 Log parameter format ETC TMC Lbin Log Parameters Parameter Data Format 67 Smart data Smart Status Page X2FSmart Data 66 Smart status page X2F This page is intentionally left blank Sense data format Sense Data Sksv Sense Data and Error Recovery MethodsSense data format ILI Sense data basic information Additional Sense code, Additional Sense code Qualifier Command inherent informationAdditional sense data length Sksv MSB Sense key inherent information Sense key Recovered Error Enable Spinup Sense Data and Error Recovery Methods Init Sense Data and Error Recovery Methods Sense Data Sense Data and Error Recovery Methods Detailed information Sense data additional informationPort CDB operation code Termination status analysis and error recovery methods Init Error Recovery Methods Recommended Command completion wait time-out Init Error Recovery Methods Recommended Sense data analysis and error recovery methods Sense data error classification 1/3 Sense data error classification 2/3 Sense data error classification 3/3 Error recovery processing procedures 1/4 Spinup Error recovery processing procedures 2/4 Error recovery processing procedures 3/4 Error recovery processing procedures 4/4 Seek error Disk Drive Error Recovery ProcessingError logging Error states and retry processing procedures Correctable data read error Disk Drive Error Recovery ProcessingWrite error Read error in uncorrectable data Auto alternate block allocation processing Other internal HDD errors Disk Drive Error Recovery Processing Error recovery processing control Disk drive errors and number of retries Sense Data and Error Recovery Methods Defect lists Defect Management Alternate block allocation Disk Media Management Defect Management Disk Media Initialization Initialization during installationIssuing the Mode Select command Disk Media Initialization Issuing the Format Unit commandMode Select command Re-initialization Format Unit command Alternate Block Allocation Processing Alternate Block Allocation Processing Overview Background Media Scan BMS modePre-Scan mode Background Media Scan BMS Conditions for operation Write command operation during a Pre-ScanBackground Media Scan BMS ∙ PER Mode Mode Page 0x1C SubPage 0x01 Background Control Mode Background Media Scan BMS Background Media Scan Log Page format Background Media Scan Log BMS Status parameter format Medium Scan parameter format Background Media Scan BMS Drive Self-Test DST Drive Self-Test DST Foreground modeSelf-test modes Background mode Test segments Matters that are common to both modesShort self-test Extended self-test Disk Media Management Drive Self-Test DST Smart Self-Monitoring Analysis and Reporting Technology Smart Self-Monitoring Analysis and Reporting Technology Data analysis ASC Ascq Failure prediction methodSmart ASC/ASCQ Smart Self-Monitoring Analysis and Reporting Technology Disk Media Management Smart thresholds Reporting function Initiator Init CommandCommon Command Set CCS Additional Sense Code This page is intentionally left blank Arre ACKAEN ALT Acronyms and Abbreviations Index Index Command Terminated Details of parameters on Mode Intermediate Condition Mode Sense Extended Persistent Reserve OUT Reservation Conflict Receive DiagnosticReport Device Identifier SET Device Identifier TB284 READER’S Comment Form This page is intentionally left blank C141-C013-01EN Page