Add and drop disks concurrently to a diskgroup in Oracle ASM, as to gain hours by one time rebalance

Adding a disk to a disk group needs rebalancing the data across newly formed diskgroup consisting newer disks. Dropping also needs similar rebalancing across diskgroup as you guess.

If you need to add and drop disks at the same time, then this trick is what you are looking for or bumped into.

As you could understood from below real world example SQL, the dgdata diskgroup is changed by adding 13 disks from new cabinet, and dropping 13 disks from old cabinet. And it worked smothly, thus we gained at least 15 hours from one time rebalancing instead of two times rebalancing. Also it worths noting that no intervention is needed, because you need to execute one SQL instead of 2.

-- Concurrently execute add/drop disk in order gain from rebalance time.

ALTER DISKGROUP DATADG
ADD DISK
    '/dev/ORACLE/ASMDISK/DATA7' NAME DATA_0007,
    '/dev/ORACLE/ASMDISK/DATA8' NAME DATA_0008,
    '/dev/ORACLE/ASMDISK/DATA9' NAME DATA_0009,
    '/dev/ORACLE/ASMDISK/DATA10' NAME DATA_0010,
    '/dev/ORACLE/ASMDISK/DATA11' NAME DATA_0011,
    '/dev/ORACLE/ASMDISK/DATA12' NAME DATA_0012,
    '/dev/ORACLE/ASMDISK/DATA13' NAME DATA_0013,
    '/dev/ORACLE/ASMDISK/DATA14' NAME DATA_0014,
    '/dev/ORACLE/ASMDISK/DATA15' NAME DATA_0015,
    '/dev/ORACLE/ASMDISK/DATA16' NAME DATA_0016,
    '/dev/ORACLE/ASMDISK/DATA17' NAME DATA_0017,
    '/dev/ORACLE/ASMDISK/DATA18' NAME DATA_0018,
    '/dev/ORACLE/ASMDISK/DATA19' NAME DATA_0019
DROP DISK
    DATADG_0000,
    DATADG_0001,
    DATADG_0002,
    DATADG_0003,
    DATADG_0004,
    DATADG_0005,
    DATADG_0006,
    DATADG_0007,
    DATADG_0008,
    DATADG_0010,
    DATADG_0011,
    DATADG_0012
REBALANCE POWER 5;