关于IOPS和MPBS的概念网上可以有很多详细的解释和介绍。
.
IOPS (Input/OutputPer Second),，即每秒读写（I/O）操作的次数总和，多用于OLTP/数据库或者小IO/小文件等场合，衡量系统的随机访问的性能。
.
我们知道，磁盘完成一个I/O请求所花费时间就磁盘本身的因素来说，跟寻道时间、转数和数据传输都有关系。
也就是说， IOPS（每秒IO次数） = 1s/(寻道时间+旋转延迟+数据传输时间)
.
而实际应用中IOPS还受到很多其他因素的影响，比如存储配置和不同操作系统上的相关配置等等（读写比例，顺序和随机，工作线程数，队列深度……），因此对比测量磁盘IOPS时应该在相同的测试基准下进行。
.
与之对应的是 MBPS ，另一个重要指标是数据吞吐量(Throughput)，指单位时间内可以成功传输的数据数量。对于大量顺序读写的应用，如VOD(Video On Demand)，则更关注吞吐量指标。
传统磁盘也就是我们常说的机械盘，如SAS, SATA磁盘等等，在Exadata的存储节点上每个cell配置了12块SAS盘或者SATA盘：
Exadata V1 存储节点上磁盘的选择： 300 GB串行连接SCSI (SAS) 磁盘 或者 1TB串行连接(SATA) 磁盘（3.5寸）
Exadata V2 存储节点上磁盘的选择： 600 GB串行连接SCSI (SAS) 磁盘 或者 2TB串行连接(SATA) 磁盘（3.5寸）
Exadata X2-2 存储节点上磁盘的选择： 600 GB 15,000 RPM 高性能SAS硬盘 或 2TB 7,200 RPM 高容量SAS硬盘（3.5寸）
Exadata X3-2 存储节点上磁盘的选择： 600 GB 15,000 RPM 高性能SAS硬盘 或 3TB 7,200 RPM 高容量SAS硬盘(3.5寸)
Exadata X4-2 存储节点上磁盘的选择： 1.2 TB 10,000 RPM 高性能SAS硬盘 或 4TB 7,200 RPM 高容量SAS硬盘(2.5寸)
关于Exadata上Database IOPS的介绍以前在 Maclean的网站上看到过一篇讲的很清楚的介绍，今天search了一下，没找到原文了，找到了一篇转载于这篇完整的：
http://storage.chinabyte.com/387/12533387.shtml
有兴趣看原文的可以联系他（liu.maclean@gmail.com）， O(∩_∩)O哈哈~
我这里稍微补充一下，其实Exadata上测试IOPS的“calibrate force”命令，本质上也是调用了“orion”，下面记录某此客户现场的实测结果：
这里我们看到，在安装Exadata时有一步“RunCalibrate”（不同版本的步骤稍有不同），我这是X2-2 1/4 Rack Image 11.2.3.2.1，采用了HP磁盘（即，每个cell12块600 GB 15,000 RPM 高性能SAS硬盘），该步骤为Step 9。 该步骤本质上是在所有cell节点上执行 “calibrate force”操作（该操作是一个只读操作）。 [root@dm01db01 tmp]# tail -f STEP-9-20121217123712.log INFO: Logging all actions in /opt/oracle.SupportTools/onecommand/tmp/STEP-9-20121217123712.log and traces in /opt/oracle.SupportTools/onecommand/tmp/STEP-9-20121217123712.trc INFO: Loading configuration file /opt/oracle.SupportTools/onecommand/onecommand.params... INFO: 2012-12-17 12:37:12 INFO: Step 9 RunCalibrate INFO: checking nodes in /opt/oracle.SupportTools/onecommand/all_group... SUCCESS: All nodes in /opt/oracle.SupportTools/onecommand/all_group are pingable and alive. INFO: Going to run calibrate, will take 10 or so minutes... INFO: Running /usr/local/bin/dcli -g /opt/oracle.SupportTools/onecommand/cell_group -l root cellcli -e calibrate force to calibrate cells... SUCCESS: Ran /usr/local/bin/dcli -g /opt/oracle.SupportTools/onecommand/cell_group -l root cellcli -e calibrate force and it returned: RC=0 dm01cel01: Calibration will take a few minutes... dm01cel01: Aggregate random read throughput across all hard disk LUNs: 1962 MBPS dm01cel01: Aggregate random read throughput across all flash disk LUNs: 4184.04 MBPS dm01cel01: Aggregate random read IOs per second (IOPS) across all hard disk LUNs: 4832 dm01cel01: Aggregate random read IOs per second (IOPS) across all flash disk LUNs: 146413 dm01cel01: Controller read throughput: 1957.14 MBPS dm01cel01: Calibrating hard disks (read only) ... dm01cel01: LUN 0_0 on drive [20:0 ] random read throughput: 166.84 MBPS, and 394 IOPS dm01cel01: LUN 0_1 on drive [20:1 ] random read throughput: 172.72 MBPS, and 406 IOPS dm01cel01: LUN 0_10 on drive [20:10 ] random read throughput: 170.37 MBPS, and 412 IOPS dm01cel01: LUN 0_11 on drive [20:11 ] random read throughput: 168.08 MBPS, and 404 IOPS dm01cel01: LUN 0_2 on drive [20:2 ] random read throughput: 171.44 MBPS, and 413 IOPS dm01cel01: LUN 0_3 on drive [20:3 ] random read throughput: 168.67 MBPS, and 420 IOPS dm01cel01: LUN 0_4 on drive [20:4 ] random read throughput: 166.21 MBPS, and 419 IOPS dm01cel01: LUN 0_5 on drive [20:5 ] random read throughput: 170.13 MBPS, and 414 IOPS dm01cel01: LUN 0_6 on drive [20:6 ] random read throughput: 170.32 MBPS, and 416 IOPS dm01cel01: LUN 0_7 on drive [20:7 ] random read throughput: 172.66 MBPS, and 402 IOPS dm01cel01: LUN 0_8 on drive [20:8 ] random read throughput: 169.86 MBPS, and 419 IOPS dm01cel01: LUN 0_9 on drive [20:9 ] random read throughput: 170.38 MBPS, and 417 IOPS dm01cel01: Calibrating flash disks (read only, note that writes will be significantly slower) ... dm01cel01: LUN 1_0 on drive [FLASH_1_0] random read throughput: 272.61 MBPS, and 19945 IOPS dm01cel01: LUN 1_1 on drive [FLASH_1_1] random read throughput: 271.77 MBPS, and 19946 IOPS dm01cel01: LUN 1_2 on drive [FLASH_1_2] random read throughput: 271.81 MBPS, and 19930 IOPS dm01cel01: LUN 1_3 on drive [FLASH_1_3] random read throughput: 272.08 MBPS, and 19908 IOPS dm01cel01: LUN 2_0 on drive [FLASH_2_0] random read throughput: 272.59 MBPS, and 20694 IOPS dm01cel01: LUN 2_1 on drive [FLASH_2_1] random read throughput: 272.45 MBPS, and 20675 IOPS dm01cel01: LUN 2_2 on drive [FLASH_2_2] random read throughput: 272.33 MBPS, and 20697 IOPS dm01cel01: LUN 2_3 on drive [FLASH_2_3] random read throughput: 272.24 MBPS, and 20707 IOPS dm01cel01: LUN 4_0 on drive [FLASH_4_0] random read throughput: 271.91 MBPS, and 19961 IOPS dm01cel01: LUN 4_1 on drive [FLASH_4_1] random read throughput: 271.84 MBPS, and 19969 IOPS dm01cel01: LUN 4_2 on drive [FLASH_4_2] random read throughput: 271.78 MBPS, and 19958 IOPS dm01cel01: LUN 4_3 on drive [FLASH_4_3] random read throughput: 271.45 MBPS, and 19960 IOPS dm01cel01: LUN 5_0 on drive [FLASH_5_0] random read throughput: 271.69 MBPS, and 19965 IOPS dm01cel01: LUN 5_1 on drive [FLASH_5_1] random read throughput: 270.85 MBPS, and 19942 IOPS dm01cel01: LUN 5_2 on drive [FLASH_5_2] random read throughput: 270.77 MBPS, and 19926 IOPS dm01cel01: LUN 5_3 on drive [FLASH_5_3] random read throughput: 271.17 MBPS, and 19907 IOPS dm01cel01: CALIBRATE results are within an acceptable range. dm01cel01: Calibration has finished. .........
在执行“calibrate force”操作期间，我们使用top观察一下cell的资源使用情况：
可以看到实际上cell上启动了6个orion 进程。
这里我们看到每个cell的平均IOPS(Aggregate random read IOs per second)和平均MBPS（Aggregate random read throughput）都是大体一致的，即：
......... dm01cel01: Aggregate random read throughput across all hard disk LUNs: 1962 MBPS dm01cel01: Aggregate random read throughput across all flash disk LUNs: 4184.04 MBPS dm01cel01: Aggregate random read IOs per second (IOPS) across all hard disk LUNs: 4832 dm01cel01: Aggregate random read IOs per second (IOPS) across all flash disk LUNs: 146413 dm01cel01: Controller read throughput: 1957.14 MBPS ......... dm01cel02: Calibration will take a few minutes... dm01cel02: Aggregate random read throughput across all hard disk LUNs: 1926 MBPS dm01cel02: Aggregate random read throughput across all flash disk LUNs: 4184.11 MBPS dm01cel02: Aggregate random read IOs per second (IOPS) across all hard disk LUNs: 4919 dm01cel02: Aggregate random read IOs per second (IOPS) across all flash disk LUNs: 137525 dm01cel02: Controller read throughput: 2014.53 MBPS ......... dm01cel03: Aggregate random read throughput across all hard disk LUNs: 1934 MBPS dm01cel03: Aggregate random read throughput across all flash disk LUNs: 4139.36 MBPS dm01cel03: Aggregate random read IOs per second (IOPS) across all hard disk LUNs: 4824 dm01cel03: Aggregate random read IOs per second (IOPS) across all flash disk LUNs: 121355 dm01cel03: Controller read throughput: 2000.5 MBPS dm01cel03: Calibrating hard disks (read only) ...
由此，我们可以推断下，如果是这款机器，满配的IOPS和MBPS是多少？
.
满配机器（14个cell）hard disk LUNs的MBPS推算： 1962*14个cell=27468
满配机器（14个cell）flash disk LUNs的MBPS推算： 4184*14个cell=58576
满配机器（14个cell）hard disk LUNs的IOPS推算： 4832*14个cell=67648
满配机器（14个cell）flash disk LUNs的IOPS推算：146413*14个cell=2049782
.
官方给出的满配的标准数据如下：
Aggregate random read throughput across all hard disk LUNs: 25GB MBPS
Aggregate random read throughput across all flash disk LUNs: 75 MBPS
Aggregate random read IOs per second (IOPS) across all hard disk LUNs: 50000
Aggregate random read IOs per second (IOPS) across all flash disk LUNs: 1500000
.
上述推断结果相比官方指标基本吻合，而且都比官方指标略高（只有flash disk LUNs的稍微偏低）。
最后还要强调一点，这里的数据仅仅适用于Exadata，Exadata是软件和硬件的完美结合
…………
