Disks


Disk groups are created using the CREATE DISKGROUP statement. This statement allows you to specify the level of redundancy:
1. NORMAL REDUNDANCY - Two-way mirroring, requiring two failure groups.
2. HIGH REDUNDANCY - Three-way mirroring, requiring three failure groups.
3. EXTERNAL REDUNDANCY - No mirroring for disks that are already protected using hardware mirroring or RAID. If you have hardware RAID it should be used in preference to ASM redundancy, so this will be the standard option for most installations.
Disk group creation
CREATE DISKGROUP disk_group_1 NORMAL REDUNDANCY
 FAILGROUP failure_group_1 DISK
 '/devices/diska1' NAME diska1,
 '/devices/diska2' NAME diska2
 FAILGROUP failure_group_2 DISK
 '/devices/diskb1' NAME diskb1,
 '/devices/diskb2' NAME diskb2;
Drop Disk group
DROP DISKGROUP disk_group_1 INCLUDING CONTENTS;
Add Disks to disk group
ALTER DISKGROUP disk_group_1 ADD DISK
 '/devices/disk*3',
 '/devices/disk*4';
Delete Disks from Disk group
ALTER DISKGROUP disk_group_1 DROP DISK diska2;
Resize Disks
-- Resize a specific disk.
ALTER DISKGROUP disk_group_1
 RESIZE DISK diska1 SIZE 100G;
-- Resize all disks in a failure group.
ALTER DISKGROUP disk_group_1
 RESIZE DISKS IN FAILGROUP failure_group_1 SIZE 100G;
-- Resize all disks in a disk group.
ALTER DISKGROUP disk_group_1
 RESIZE ALL SIZE 100G;
Undrop diskgroup
ALTER DISKGROUP disk_group_1 UNDROP DISKS;
Rebalancing Diskgroup
ALTER DISKGROUP disk_group_1 REBALANCE POWER 5;
Disk group mount/unmount
ALTER DISKGROUP ALL DISMOUNT;
ALTER DISKGROUP ALL MOUNT;
ALTER DISKGROUP disk_group_1 DISMOUNT;
ALTER DISKGROUP disk_group_1 MOUNT;

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