Crete Disk Group:
Create Disk groups using the CREATE DISKGROUP statement and specify the level of redundancy.
Disk group redundancy types:-
NORMAL REDUNDANCY - Two-way mirroring, requiring two failure groups.
HIGH REDUNDANCY - Three-way mirroring, requiring three failure groups.
EXTERNAL REDUNDANCY - No mirroring for disks that are already protected using hardware RAID or mirroring.
SQL> CREATE DISKGROUP data NORMAL REDUNDANCY
FAILGROUP failure_group_1 DISK '/dev/sda1' NAME dataa1,'/dev/sda2' NAME dataa2,
FAILGROUP failure_group_2 DISK '/dev/sdb1' NAME datab1,'/dev/sdb2' NAME datab2;
Drop Disk Group:
Drop disk group using DROP DISKGROUP statement.
SQL> DROP DISKGROUP data INCLUDING CONTENTS;
Alter Disk Group:
Add or remove disks from disk groups Using ALTER DISKGROUP statement. You can also use wildcard "*" to reference disks.
Add a disk.
SQL> ALTER DISKGROUP data ADD DISK '/dev/datac1', '/dev/datac2';
Add all reference disks
SQL> ALTER DISKGROUP data ADD DISK '/dev/datad*;
Drop/remove a disk.
SQL> ALTER DISKGROUP data DROP DISK datab2;
The UNDROP command used to undo only pending drop of disks. After you drop the disks you cannot revert.
SQL> ALTER DISKGROUP data UNDROP DISKS;
Diskgroup Rebalance:
Disk groups can be rebalanced manually Using REBALANCE clause and you can modify the POWER clause default value.
SQL> ALTER DISKGROUP disk_group_1 REBALANCE POWER 5;
MOUNT and DISMOUNT DiskGroups:
Normally Disk groups are mounted at ASM instance startup and dismounted at shutdown. Using MOUNT and DISMOUNT options you can make one or more Disk Groups available or unavailable.
SQL> ALTER DISKGROUP data MOUNT;
SQL> ALTER DISKGROUP data DISMOUNT;
SQL> ALTER DISKGROUP ALL MOUNT;
SQL> ALTER DISKGROUP ALL DISMOUNT;
DiskGroup Check:
Use CHECK ALL to verify the internal consistency of disk group metadata and repair in case of any error.
SQL> ALTER DISKGROUP data CHECK ALL;
DiskGroup resize:
Resize the one or all disks in the Diskgroup.
Resize all disks in a failure group.
SQL> ALTER DISKGROUP data RESIZE DISKS IN FAILGROUP failure_group_1 SIZE 1024G;
Resize a specific disk.
SQL> ALTER DISKGROUP data RESIZE DISK dataa1 SIZE 1024G;
Resize all disks in a disk group.
SQL> ALTER DISKGROUP data RESIZE ALL SIZE 1024G;
Regards,
Satishbabu Gunukula
http://www.oracleracexpert.com/
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raju
Great and Useful Article.
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