Oracle Error Message
ORA-15074: diskgroup string requires rebalance completion
Reason for the Error
An attempt was made to repeatedly add or drop disks from a diskgroup. ASM could not perform the operation given the current state of the diskgroup.
Solution
Manually invoke the ALTER DISKGROUP REBALANCE command and allow the rebalance to run to completion. Alternatively, invoke the ALTER DISKGROUP UNDROP DISKS command and allow the rebalance to run to completion. After the rebalance has completed, retry the operation.