Exadata-Storage-Architecture

Each storage server has 12 physical hard disks and 16 flash disks by default 

when hard disk is found, the operating system determines the device driver needed and create a block device called " lun " for application access. hard disks acts as first layer for luns. create celldisks using physical disks(luns) available on the server. 

    Physical Disk > Luns > celldisks > griddisk > Asmdisk  

Using Physical disks celldisks are created 

we can list physical disks using cellcli, following command displays hard disks and flash disks attached to the storage server 

cellcli> list physicaldisk

LUN(Logical Unit Number) 

LUN is automatically created on each physical disk
# on storage server issue command # lsscsi to list all luns 
these luns are used to create cell disks. First 2 disks contain the system AREA, we can see information using fdisk # list the partitions available on first 2 physical disks 
# fdisk -l /dev/sda
# fdisk -l /dev/sdb

CellCLI> list lun attributes name, deviceName, isSystemLun, physicalDrives, lunSize
( This output tells about the both physical disks and flash disks available on server )

using physical harddisks and flashdisks, celldisks are created using cellcli 

cellcli>  create celldisk all ( This command will create the cell disks for both physical hard disks and flash disks)

cellcli> list celldisks (This command will display all cell disks on the storage server) 

using celldisks we can create griddisks using cellcli as follows

cellcli> create griddisk <GroupName> celldisk = <Cell-Disk-Name>, size =< >

following command displays all griddisks available on the storage server

cellcli> list griddisk 

--Nikhil Tatineni--

--Exadata--