SCSI命令概述(翻译)

1、Improving Networks Worldwide.UNH 互操作性互操作性实验实验室室SCSI 命令概述Improving Networks Worldwide.物理物理层数据链路层数据传输层应用层3SCSI Overview陈述主题 命令摘要 命令选择释义 附加意义上的代码及资格4SCSI OverviewCDB 命令数据程序块 命令由CDBs定义 每个对象都有他自己的 CDB CDBs 由多种SCSI标准定义 拥有固定和变化的长度变量 In SAS: 囊括在一个指令框架中5SCSI OverviewSCSI Command SetsSPC-4 SCSI Primary Comman

2、ds Version 4 命令对于所有的方法类型普遍适用SBC-3 SCSI Block Command Version 3 命令针对特定的块设备 (硬盘)SSC-2 SCSI Streaming Commands Version 2 命令针对特定的流设备(磁盘驱动)MMC-4 SCSI Multi Media Commands Version 4 命令针对特定的多媒体设备(CD/DVD)6SCSI OverviewCommon SCSI Commands in SAS Read Commands READ (6) (SSC and SBC)* READ (10) (SBC) READ (12

3、) (SBC) READ (16) (SBC) READ (32) (SBC)*不同的域定义使用相同的 CDB长度7SCSI OverviewCommand SCSI Commands in SAS Write Commands WRITE (6) (SSC and SBC)* WRITE (10) (SBC) WRITE (12) (SBC) WRITE (16) (SBC) WRITE (32) (SBC)*Different Field Definitions, same CDB Length8SCSI Overview诊断与初始化指令 读缓冲(SPC) 写缓冲 (SPC) 询问(SPC

4、) 测试单元就绪(SPC) 模式识别(SPC) 模式选择(SPC) 日志识别(SPC) 日志选择(SPC) 读取归类(SPC) REPORT LUNS (SPC) READ BUFFER (SPC) WRITE BUFFER (SPC) INQUIRY (SPC) TEST UNIT READY (SPC) MODE SENSE (SPC) MODE SELECT (SPC) LOG SENSE (SPC) LOG SELECT (SPC) READ ATTRIUBUTE (SPC) REPORT LUNS (SPC)9SCSI Overview数据块指定的指令 READ CAPACITY V

5、ERIFY WRITE AND VERIFY READ LONG WRITE LONG Many more10SCSI OverviewStreaming Specific Commands LOAD UNLOAD LOCATE (16) PREVENT ALLOW MEDIUM REMOVAL READ BLOCK LIMITS READ POSITION REWIND SET CAPACITY SPACE (16)11SCSI OverviewREAD (16) Command OP 代码: 88h Specifies the command 读保护: 关于写保护检查的多种设定12SCSI

6、 OverviewREAD (16) Command DPO Disable Page Out Bit用于最优化登录目标设备的缓存 Set to 1 tells the target that data at this Logical Block Address is not likely to be accessed again in the near future and that the target can remove it from its local cacheSet to 1告诉目标在这个逻辑区块地址中的数据在不久的将来无法再次接近并且目标可在将它从它的本地缓存中移除13SCS

7、I OverviewREAD (16) Command FUA and FUA_NV Force Unit Access (Non-Volatile) Used to override the targets internal caching and force it to access the media 适用于目标内部缓存并且指示其接近媒介14SCSI OverviewREAD (16) Command Logical Block Address (LBA) The address on the medium that the initiator would like to read In

8、ternally, the target converts the LBA to a (Cylinder, Sector, Head) address Transparent to the computer system and user逻辑区块地址在内部，对象将LBA转化成一个地址，此地址对计算机系统和用户而言显而易见15SCSI OverviewREAD (16) Command Transfer Length Specifies the length in contiguous logical units to be transferred in this command Logical

9、 unit is typically 512-bytes (1 Block) 本地单元使典型的512字节（1数据块）在此对象中指定在临近逻辑单元上被转移的长度16SCSI OverviewREAD (16) Command Restricted for MMC-4 Used for the MMC-4 Version of this command17SCSI OverviewREAD (16) Command Group Number Used to collect performance statistics of different groups of commands Applicat

10、ion As performance vs. Applications Bs performance用于收集不同组别命令的执行统计18SCSI OverviewREAD (16) Command ControlStandard SCSI Control BytesDefined in SAM-4Has a consistently defined meaning across all commandsFound only on fixed-length CDB commands翻译：标准SCSI控制字节19SCSI OverviewWRITE (16) Command OP Code: 8Ah

11、 Specifies the command WD Protect: Various settings regarding the write protection checking20SCSI OverviewWRITE (16) Command DPO Disable Page Out BitUsed to optimize caching onboard the target device Set to 1 tells the target that data at this Logical Block Address is not likely to be accessed again

12、 in the near future and that the target can remove it from its local cache21SCSI OverviewWRITE (16) Command FUA and FUA_NV Force Unit Access (Non-Volatile) Used to override the targets internal caching and force it to access the media 22SCSI OverviewWRITE (16) CommandLogical Block Address (LBA) The

13、address on the medium that the initiator would like to read Internally, the target converts the LBA to a (Cylinder, Sector, Head) address Transparent to the computer system and user23SCSI OverviewWRITE (16) CommandTransfer Length Specifies the length in contiguous logical units to be transferred in

14、this command Logical unit is typically 512-bytes (1 Block) 24SCSI OverviewWRITE (16) Command Restricted for MMC-4 Used for the MMC-4 Version of this command25SCSI OverviewWRITE (16) Command Group Number Used to collect performance statistics of different groups of commands Application As performance

15、 vs. Applications Bs performance26SCSI OverviewWRITE (16) Command ControlStandard SCSI Control BytesDefined in SAM-4Has a consistently defined meaning across all commandsFound only on fixed-length CDB commands27SCSI OverviewTEST UNIT READY CommandOP Code: 00h Specifies the commandControl Bits are ty

16、pically zero Defined in SAM-4Result: 6 Byte CDB consisting of entirely 0s28SCSI OverviewTEST UNIT READY CommandAlso:CHECK CONDITION NOT READY POWER ON OCCURED29SCSI OverviewINQUIRY CommandOP Code: 12h Specifies the CommandEVPD: Enable Vital Product Data Set to zero, the device returns standard inqui

17、ry data Set to one, enables the page code field 设置为0，设备返回普通的询问信息设置为1，启用页面代码字段30SCSI OverviewINQUIRY CommandPage Code: Specifies the page code to return. Pages are defined in SAM-4, SPC-4, and technology specific standardsAllocation Length specifies the length of inquiry data the initiator is prepare

18、d to accept in bytes定位长度决定了发起者准备接收的询问信息的长度31SCSI OverviewREPORT LUNS CommandOP Code: A0h Specifies the commandSelect Report: 32SCSI OverviewREPORT LUNS CommandAllocation Length should be at least 16 bytesIf the allocation length is insufficient to report all the LUNs on the device, the device shall report only what it is able to report翻译：定位长度至少要有16字节翻译：如果定位长度不足以报告设备上所有的逻辑单元，硬盘应该只报告它可以报告的单元33SCSI OverviewAdditional Sense CodesValues returned in a Response Frame (SAS) in the event that a command could not be completedSo many possible problems that a qualifier is used