An Exadata X2-2 storage cell contains 12 disks. While you should not need to look at them via iostat to measure performance, as metrics are available via dbconsole, enterprise manager and asm disk views, it can sometimes be useful to be able to take a quick look at the system.
Ways to map your Exadata devices to /dev/sd*
lsscsi
[root@ed2hcell01 ~]# lsscsi [0:0:20:0] enclosu SUN HYDE12 0341 - [0:2:0:0] disk LSI MR9261-8i 2.90 /dev/sda [0:2:1:0] disk LSI MR9261-8i 2.90 /dev/sdb [0:2:2:0] disk LSI MR9261-8i 2.90 /dev/sdc [0:2:3:0] disk LSI MR9261-8i 2.90 /dev/sdd [0:2:4:0] disk LSI MR9261-8i 2.90 /dev/sde [0:2:5:0] disk LSI MR9261-8i 2.90 /dev/sdf [0:2:6:0] disk LSI MR9261-8i 2.90 /dev/sdg [0:2:7:0] disk LSI MR9261-8i 2.90 /dev/sdh [0:2:8:0] disk LSI MR9261-8i 2.90 /dev/sdi [0:2:9:0] disk LSI MR9261-8i 2.90 /dev/sdj [0:2:10:0] disk LSI MR9261-8i 2.90 /dev/sdk [0:2:11:0] disk LSI MR9261-8i 2.90 /dev/sdl [1:0:0:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdm [1:0:1:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdn [1:0:2:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdo [1:0:3:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdp [2:0:0:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdq [2:0:1:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdr [2:0:2:0] disk ATA MARVELL SD88SA02 D20Y /dev/sds [2:0:3:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdt [3:0:0:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdu [3:0:1:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdv [3:0:2:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdw [3:0:3:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdx [4:0:0:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdy [4:0:1:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdz [4:0:2:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdaa [4:0:3:0] disk ATA MARVELL SD88SA02 D20Y /dev/sdab
The LSI devices (hightlighted in red) are the physical disks, the MARVELL (in blue) are the Flash devices.
cellcli
The ‘list celldisk detail’ command gives information about the celldisks. Note, the command output is very long, so pipe it to a file!
[root@ed2hcell01 ~]# cellcli -e list celldisk detail name: CD_00_ed2hcell01 comment: creationTime: 2011-02-15T12:22:02+00:00 deviceName: /dev/sda devicePartition: /dev/sda3 diskType: HardDisk errorCount: 0 freeSpace: 0 id: 8f63def6-0ca7-448a-a3bd-76e5572af5f5 interleaving: none lun: 0_0 raidLevel: 0 size: 528.734375G status: normal name: CD_01_ed2hcell01 comment: creationTime: 2011-02-15T12:22:06+00:00 deviceName: /dev/sdb devicePartition: /dev/sdb3 diskType: HardDisk errorCount: 0 freeSpace: 0 id: 41f37430-2beb-4062-9a03-ae801f411520 interleaving: none lun: 0_1 raidLevel: 0 size: 528.734375G status: normal name: CD_02_ed2hcell01 comment: creationTime: 2011-02-15T12:22:06+00:00 deviceName: /dev/sdc devicePartition: /dev/sdc diskType: HardDisk errorCount: 0 freeSpace: 0 id: a9fc2181-10fc-498e-a902-9bb5cb47441c interleaving: none lun: 0_2 raidLevel: 0 size: 557.859375G status: normal
<snip>
Note the lines highlighted in red:- on the first 2 disks the celldisks sit in the partition /dev/sd*3 to allow space for the software and operating system. On the remaining disks the cells have access to the whole disks.
This means that in iostat you cannot separate out the load for different ASM diskgroups whose griddisks share the same celldisk. You can see which celldisks are used by your griddisk by using
[root@ed2hcell01 ~]#cellcli -e list griddisk detail
Again the output to this command can be long, and it is better piped to a file.
name: DATA_DM01_CD_00_ed2hcell01 availableTo: cellDisk: CD_00_ed2hcell01 comment: creationTime: 2011-02-15T12:26:29+00:00 diskType: HardDisk errorCount: 0 id: a8c155f9-64c4-4604-adfd-3771ac93c35a offset: 32M size: 392G status: active
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