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1、Improving Networks Worldwide.UNH 互操作性实验实验室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 Overview CDB 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 Overview SCSI Command Sets SPC-4 SCSI Primary Commands
2、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 Overview READ (16) Command OP 代码: 88h Specifies the command 读保护: 关于写保护检查的多种设定12SCS
6、I Overview READ (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 cache Set 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1
7、3SCSI Overview READ (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 Overview READ (16) Command Logical Block Address (LBA) The address on the medium that the initiator would like to
8、read Internally, 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 Overview READ (16) Command Transfer Length Specifies the length in contiguous logical units to be transferred in this command
9、 Logical 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 Overview READ (16) Command Restricted for MMC-4 Used for the MMC-4 Version of this command17SCSI Overview READ (16) Command Group Number Used to collect performance statistics of different groups of command
10、s Application As performance vs. Applications Bs performance用于收集不同组别命令的执行统计18SCSI Overview READ (16) Command ControlStandard SCSI Control Bytes Defined in SAM-4 Has a consistently defined meaning across all commands Found only on fixed-length CDB commands翻译：标准SCSI控制字节19SCSI Overview WRITE (16) Comma
11、nd OP Code: 8Ah Specifies the command WD Protect: Various settings regarding the write protection checking20SCSI Overview WRITE (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 b
12、e accessed again in the near future and that the target can remove it from its local cache21SCSI Overview WRITE (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 Overview WRITE (16) Command Logical Bloc
13、k Address (LBA) The 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 Overview WRITE (16) Command Transfer Length Specifies the length in contiguous logical units
14、 to be transferred in this command Logical unit is typically 512-bytes (1 Block) 24SCSI Overview WRITE (16) Command Restricted for MMC-4 Used for the MMC-4 Version of this command25SCSI Overview WRITE (16) Command Group Number Used to collect performance statistics of different groups of commands Ap
15、plication As performance vs. Applications Bs performance26SCSI Overview WRITE (16) Command ControlStandard SCSI Control Bytes Defined in SAM-4 Has a consistently defined meaning across all commands Found only on fixed-length CDB commands27SCSI OverviewTEST UNIT READY Command OP Code: 00h Specifies the command Control Bits are typically zero Defined in SAM-4 Result: 6 Byte CDB consisting of entirely 0s28SCSI OverviewTEST UNIT READY CommandAlso: CHECK CONDITION NOT READY POWER ON OCCURED29SCSI OverviewINQUIRY Command OP Code: 12h Specifies the Command
