Exadata Software - Oracle Exadata Recipes: A Problem-Solution Approach - page 42

[root@cm01dbm01 ~]# /u01/app/11.2.0.3/grid/bin/ocrconfig -showbackup
cm01dbm01 2012/07/27 12:59:47 /u01/app/11.2.0.3/grid/cdata/cm01-cluster/backup00.ocr
cm01dbm01 2012/07/27 08:59:47 /u01/app/11.2.0.3/grid/cdata/cm01-cluster/backup01.ocr
cm01dbm01 2012/07/27 04:59:46 /u01/app/11.2.0.3/grid/cdata/cm01-cluster/backup02.ocr
cm01dbm01 2012/07/26 04:59:45 /u01/app/11.2.0.3/grid/cdata/cm01-cluster/day.ocr
cm01dbm01 2012/07/13 20:59:24 /u01/app/11.2.0.3/grid/cdata/cm01-cluster/week.ocr
cm01dbm01 2011/05/03 16:11:19 /u01/app/11.2.0/grid/cdata/cm01-cluster/
backup_20110503_161119.ocr
[root@cm01dbm01 ~]#

On Exadata, the clusterware voting disks are also stored in an Oracle ASM disk group, as indicated:

[root@cm01dbm01 ~]# /u01/app/11.2.0.3/grid/bin/crsctl query css votedisk
## STATE File Universal Id File Name Disk group
-- ----- ----------------- --------- ----------
1. ONLINE 948f35d3d9c44f94bfe7bb831758104a (o/192.168.10.4/DBFS_DG_CD_06_cm01cel02) [DBFS_DG]
2. ONLINE 61fb620328a24f87bf8c4a0ac0275cd1 (o/192.168.10.5/DBFS_DG_CD_05_cm01cel03) [DBFS_DG]
3. ONLINE 0bfafeda13974f16bf4d90ef6317aa7f (o/192.168.10.3/DBFS_DG_CD_05_cm01cel01) [DBFS_DG]
Located 3 voting disk(s).
[root@cm01

dbm01 ~]

You can see that Exadata builds three copies of the voting disk, each stored in the DBFS_DG ASM disk group, with
copies on each of your three Exadata Storage Servers.

■ on Exadata Half Rack and full Rack models, oracle will create three copies of the voting disk on the first three
grid disks containing the DBFS_DG disk group and not containing the System Area.

Note

How It Works
On Exadata, Oracle has elected to store the Oracle Cluster Registry (OCR) and voting disks on Oracle ASM disk groups,
mapped to Exadata storage server grid disks. The OCR and voting disks are typically stored in the DBFS_DG ASM disk
group and associated grid disks.
It is worth mentioning Oracle's rationale for placing the OCR and voting disks in the DBFS_DG ASM disk group.
Based on our experience, which started with Oracle Exadata X2-2 models in late 2010, a default Exadata installation
will create and configure storage server grid disks and associated ASM disk groups based on customer requirements.
It will also create a set of grid disks prefixed with DBFS_DG , intended for use with Oracle DBFS ASM disk groups.
Contrary to the other grid disks, which span all 12 cell disks on all storage server nodes, the DBFS_DG grid disks are only
built on the 10 cell disks that do not contain the storage cell's System Area. This is Oracle's solution to addressing a
potential “gap” of unusable capacity.

CellCLI> list griddisk where name like 'DBFS_DG_.*' attributes name,cellDisk,size

DBFS_DG_CD_02_cm01cel01 CD_02_cm01cel01 29.125G

DBFS_DG_CD_03_cm01cel01 CD_03_cm01cel01 29.125G

DBFS_DG_CD_04_cm01cel01 CD_04_cm01cel01 29.125G

DBFS_DG_CD_05_cm01cel01 CD_05_cm01cel01 29.125G

DBFS_DG_CD_06_cm01cel01 CD_06_cm01cel01 29.125G

DBFS_DG_CD_07_cm01cel01 CD_07_cm01cel01 29.125G

DBFS_DG_CD_08_cm01cel01 CD_08_cm01cel01 29.125G

DBFS_DG_CD_09_cm01cel01 CD_09_cm01cel01 29.125G

DBFS_DG_CD_10_cm01cel01 CD_10_cm01cel01 29.125G