The SQL statements presented in the following example demonstrate the interactions of disk discovery with the ADD DISK operation.
Assume that disk discovery identifies the following disks in directory /devices:
/devices/diska1 -- member of data1 /devices/diska2 -- member of data1 /devices/diska3 -- member of data1 /devices/diska4 -- member of data1 /devices/diska5 -- candidate disk /devices/diska6 -- candidate disk /devices/diska7 -- candidate disk /devices/diska8 -- candidate disk /devices/diskb1 -- member of data1 /devices/diskb2 -- member of data1 /devices/diskb3 -- member of data1 /devices/diskb4 -- member of data2 /devices/diskc1 -- member of data2 /devices/diskc2 -- member of data2 /devices/diskc3 -- member of data3 /devices/diskc4 -- candidate disk /devices/diskd1 -- candidate disk /devices/diskd2 -- candidate disk /devices/diskd3 -- candidate disk /devices/diskd4 -- candidate disk /devices/diskd5 -- candidate disk /devices/diskd6 -- candidate disk /devices/diskd7 -- candidate disk /devices/diskd8 -- candidate disk
You can query the V$ASM_DISK view to display the status of Oracle ASM disks. See "Views Containing Oracle ASM Disk Group Information".
The following statement would fail because /devices/diska1 through /devices/diska4 currently belong to the disk group data1.
ALTER DISKGROUP data1 ADD DISK
'/devices/diska*';
The following statement successfully adds disks /devices/diska5 through /devices/diska8 to data1. Because no FAILGROUP clauses are included in the ALTER DISKGROUP statement, each disk is assigned to its own failure group. The NAME clauses assign names to the disks, otherwise they would have been assigned system-generated names.
ALTER DISKGROUP data1 ADD DISK
'/devices/diska5' NAME diska5,
'/devices/diska6' NAME diska6,
'/devices/diska7' NAME diska7,
'/devices/diska8' NAME diska8;
The following statement would fail because the search string matches disks that are contained in other disk groups. Specifically, /devices/diska4 belongs to disk group data1 and /devices/diskb4 belongs to disk group data2.
ALTER DISKGROUP data1 ADD DISK
'/devices/disk*4';
The following statement would successfully add /devices/diskd1 through /devices/diskd8 to disk group data1. This statement runs with a rebalance power of 5, and does not return until the rebalance operation is complete.
ALTER DISKGROUP data1 ADD DISK
'/devices/diskd*'
REBALANCE POWER 5 WAIT;
If /devices/diskc3 was previously a member of a disk group that no longer exists, then you could use the FORCE option to add the disk as a member of another disk group. For example, the following use of the FORCE clause enables /devices/diskc3 to be added to data2, even though it is a current member of data3. For this statement to succeed, data3 cannot be mounted.
ALTER DISKGROUP data2 ADD DISK
'/devices/diskc3' FORCE;