Oracle Exam 1Z0-070 Topic 4 Question 2 Discussion

You may need to replace a physical disk because the disk is in warning - predictive failure status. The predictive failure status indicates that the physical disk will soon fail, and should be replaced at the earliest opportunity. The Oracle ASM disks associated with the grid disks on the physical drive are automatically dropped, and an Oracle ASM rebalance relocates the data from the predictively failed disk to other disks.

Note: After the physical disk is replaced, the grid disks and cell disks that existed on the previous disk in that slot are re-created on the new physical disk. If those grid disks were part of an Oracle ASM group, then they are added back to the disk group, and the data is rebalanced on them, based on the disk group redundancy and ASM_POWER_LIMIT parameter.

References:

http://docs.oracle.com/cd/E80920_01/DBMMN/maintaining-exadata-storage-servers.htm#DBMMN21047