How Oracle Works on Exadata - Oracle Exadata Recipes: A Problem-Solution Approach - page 55

Exadata cell disks are built on LUNs. A CellCLI listing of cell disks is provided:

CellCLI> list celldisk attributes name,deviceName,devicePartition,interleaving,lun,size
CD_00_cm01cel01 /dev/sda /dev/sda3 normal_redundancy 0_0 528.734375G
CD_01_cm01cel01 /dev/sdb /dev/sdb3 normal_redundancy 0_1 528.734375G
CD_02_cm01cel01 /dev/sdc /dev/sdc normal_redundancy 0_2 557.859375G
... Additional cell disks omitted
FD_00_cm01cel01 /dev/sds /dev/sds none 1_0 22.875G
FD_01_cm01cel01 /dev/sdr /dev/sdr none 1_1 22.875G
FD_02_cm01cel01 /dev/sdt /dev/sdt none 1_2 22.875G
... Additional flash cell disks omitted

CellCLI>

The CellCLI list celldisk output tells us the following:

• There is one cell disk per LUN.

• We're displaying cell disks for both hard disks and flash disks.

devicePartition for cell disks CD_00_cm01cel01 and CD_01_cm01cel01 , which reside on
LUNs on the first two physical disks, map to the /dev/sda3 and /dev/sdb3 partitions. This is
consistent with what we expected from previous fdisk listings.

• The

• The size of all but the first two disks equals the size of the LUN. For the cell disk built on LUNs

that contain a System Area, Exadata automatically carves the cell disk boundaries to reside
outside the System Area partitions.

normal_redundancy interleaving • Each of the cell disks built on hard disks is defined with a

attribute, in this case.

How It Works
The storage grid in the Exadata Database Machine is made up of multiple storage servers, or storage cells. Each
storage cell has 12 physical SAS disks. On the first two physical disks, Oracle reserves a small chunk of storage for the
System Area. The System Area is used for the Oracle Linux operating system, the Exadata Storage Server software,
log and alert files, and a metadata repository. The System Area is small in size—roughly 30 GB. The remainder of the
capacity for the first two disks and all of the other ten disks are dedicated to database storage. Figure 3-1 shows the
storage mapping for a disk containing the System Area, and Figure 3-2 shows mapping details for a non-System
Area device.