Some Views:
- V$ASM
- V$ASM_ATTRIBUTE
- V$ASM_DISK
- V$ASM_DISKGROUP
- V$ASM_DISK_STAT
- V$ASM_FILE
- V$ASM_OPERATION
- V$ASM_USER
Redundancy level of the disk group:
- Normal Redundancy: 2-way mirroring by default for most file types and the maximum oracle asm file sizes for disk group is 5.8 TB
- High Redundancy:3-way mirroring for all files and the maximum oracle asm file sizes for disk group is 3.9 TB.
- External Redundancy: If you do not want mirroring by Oracle ASM, but for RAID disk and the maximum oracle asm file sizes for disk group is 16 TB.
CREATING DISK GROUP
From Oracle’s docs:
Oracle recommends that the allocation unit (AU) size for a disk group be set to 4 megabytes (MB).
Controller techA:
/devices/diska1
/devices/diska2
Controller techB:
/devices/diskb1
/devices/diskb2
Controller techC:
/devices/diskc1
/devices/diskc2
- Normal Redundancy:
CREATE DISKGROUP data NORMAL REDUNDANCY
FAILGROUP techA DISK
‘/devices/diska1’ NAME tech1,
‘/devices/diska2’ NAME tech2
FAILGROUP techB DISK
‘/devices/diskb1’ NAME techb1,
‘/devices/diskb2’ NAME techb2
ATTRIBUTE ‘au_size’=’4M’,
‘compatible.asm’ = ‘11.2’,
‘compatible.rdbms’ = ‘11.2’,
‘compatible.advm’ = ‘11.2’;
You can drop the disk:
DROP DISKGROUP DATA;
or
DROP DISKGROUP DATA FORCE;
Normal Redundancy with ORC and Voting Files:
From Oracle’s docs:
Oracle Clusterware files a minimum of three disk devices or three failure groups is required with a normal redundancy for disk group.
CREATE DISKGROUP ORC_DATA NORMAL REDUNDANCY
FAILGROUP techA DISK ‘/devices/diska1’ NAME techorc1,
FAILGROUP techB DISK ‘/devices/diskb2’ NAME techorc2
QUORUM FAILGROUP techC DISK ‘/devices/diskc3’
ATTRIBUTE ‘compatible.asm’ = ‘11.2.0.0.0’;
You can drop the disk:
DROP DISKGROUP OCR_DATA;
or
DROP DISKGROUP OCR_DATA FORCE;
- High Redundancy:
CREATE DISKGROUP DATA HIGH REDUNDANCY
FAILGROUP techA DISK
‘/devices/diska1’ NAME tech1,
‘/devices/diska2’ NAME tech2
FAILGROUP techB DISK
‘/devices/diskb1’ NAME techb1,
‘/devices/diskb2’ NAME techb2
FAILGROUP techC DISK
‘/devices/diskc1’ NAME techc1,
‘/devices/diskc2’ NAME techc2
ATTRIBUTE ‘au_size’ = ‘4M’,
‘compatible.asm’ = ‘11.2’,
‘compatible.rdbms’ = ‘11.2’,
‘compatible.advm’ = ‘11.2’;
You can drop the disk:
DROP DISKGROUP DATA;
or
DROP DISKGROUP DATA FORCE;
- External Redundancy:
CREATE DISKGROUP DATA EXTERNAL REDUNDANCY DISK ‘/devices/diska1’ NAME tech1;
- Mount and Dismount a disk group:
- ALTER DISKGROUP DATA MOUNT;
- ALTER DISKGROUP DATA DISMOUNT;
Oracle Cluster Registry and Voting Files in Oracle ASM Disk Groups
From Oracle’s docs:
Voting files manage information about node membership. OCR is a system that manages cluster and Oracle Real Application Clusters (Oracle RAC) database configuration information. A quorum failure group is a special type of failure group and disks in these failure groups do not contain user data. A quorum failure group is not considered when determining redundancy requirements in respect to storing user data. However, a quorum failure group counts when mounting a disk group.
Column in views to check informations about the failure group type and contents:
- FAILGROUP_TYPE in V$ASM_DISK or V$ASM_DISK_STAT;
- VOTING_FILE in V$ASM_DISK or V$ASM_DISK_STAT.
- Manually rebalancing a disk group:
ALTER DISKGROUP DATA REBALANCE POWER 5 WAIT;
SELECT * FROM V$ASM_OPERATION;
or
ALTER DISKGROUP DATA REBALANCE POWER 5;
SELECT * FROM V$ASM_OPERATION;
- DISK_REPAIR_TIME: Specify the time that the disk will be drop after him was put offline.
- ALTER DISKGROUP data OFFLINE DISK TECH1 DROP AFTER 2m; –disk will be drop after 2 minutes
- ALTER DISKGROUP data OFFLINE DISK TECH1; — using disk repair time
- V$ASM_DISK for header status (HEADER_STATUS column):
- MEMBER: A disk that have a disk group name in the disk header;
- CANDIDATE or PROVISIONED: A disk that have not yet been assigned to a disk group;
- FORMER: A disk that was a member of a disk group, but was dropped cleanly from the disk group.
Queriyng the view:
SELECT name, header_status, path FROM V$ASM_DISK WHERE path LIKE ‘/devices/disk%’;
Addying a disk to a disk group:
ALTER DISKGROUP DATA ADD DISK
‘/devices/diska5’ NAME tech5,
‘/devices/diska6’ NAME tech6,
‘/devices/diskb7’ NAME tech7,
‘/devices/diskc8’ NAME tech8;
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References:
Oracle® Automatic Storage Management Administrator’s Guide 4 Administering Oracle ASM Disk Groups
