Storage Administration - Oracle Exadata Recipes: A Problem-Solution Approach - page 248

One fact to note, as mentioned in the solution of this recipe, is that high redundancy is not supported on an
Exadata Quarter Rack.
In summary, Oracle ASM on Exadata mirrors storage similarly to how extents are mirrored on non-Exadata
systems. The primary differences are that external redundancy is not an option and that Exadata automatically places
mirrored extents on different storage servers. Since external redundancy is not an option with Exadata, be sure to take
into consideration your desired protection level when conducting Exadata storage capacity planning.

9-5. Displaying ASM Partner Disk Relationships on Exadata
Problem
As an Exadata administrator, you wish to understand or confirm where ASM disk group mirror extents reside in order
to validate that your database storage platform is offering a suitable level of disk protection.

Solution
In an Oracle ASM instance, X$KFDPARTNER provides information on the ASM disk group partner relationship. Log in to
your Oracle ASM instance and connect as SYSASM , and then issue the query in Listing 9-9 to demonstrate this relationship.

■ in the following query, we're restricting our output to examine the aSm partner disk relationships to the third
cell disk on each of our three storage cells and the DATA_CM01 aSm disk group.

Note

Listing 9-9. lst09-09-asm-partnerdisk.sql
SQL> SELECT dg.name,
d.disk_number "Disk#",
d.path disk_path,
p.number_kfdpartner ,
pd.path partner_path
FROM x$kfdpartner p,
v$asm_disk d,
v$asm_disk pd,
v$asm_diskgroup dg
WHERE p.disk=d.disk_number
and p.grp=d.group_number
and p.number_kfdpartner = pd.disk_number
and p.grp=pd.group_number
and d.group_number=dg.group_number
and dg.name='DATA_CM01'
and d.path like '%DATA_CD_03%'
ORDER BY 1, 2, 3;

Disk Primary Primary Partner Partner
Group Disk Path Disk Path
--------- ------ ----------------------------------- ------ -----------------------------------
DATA_CM01 3 o/192.168.10.5/DATA_CD_03_cm01cel03 29 o/192.168.10.3/DATA_CD_03_cm01cel01
DATA_CM01 3 15 o/192.168.10.4/DATA_CD_06_cm01cel02
DATA_CM01 3 19 o/192.168.10.4/DATA_CD_04_cm01cel02