Explanation/Reference:
Explanation:
ASM Fast Mirror Resync
Enabled when COMPATIBLE.RDBMS >= 11.1
Whenever ASM is unable to write an extent, ASM takes the associated disk offline. If the corresponding disk group uses ASM mirroring (NORMAL or HIGH redundancy), at least one mirror copy of the same extent exists on another disk in the disk group.
Before Oracle Database 11g, ASM assumed that an offline disk contains only stale data and no longer reads from such disks. Shortly after a disk is put offline, ASM drops it from the disk group by re-creating the extents allocated to the disk on the remaining disks in the disk group using mirrored extent copies. This process is quite resource intensive and can take hours to complete. If the disk is replaced or the failure is repaired, the disk must be added again and another rebalance operation must take place.
D60488GC11
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 8 - 32