ASM Features and Benefits
• Provides online disk reconfiguration and dynamic rebalance by power limit
• Provides redundancy on a per-file basis in a disk group
• ASM divides files into extents and spreads the extents for each file evenly across all the disks.
It uses an index technique to track the placement of each extent. When the storage capacity
increase or decrease, ASM does not restripe all the data but moves an amount of data proportional
to the amount of storage added or removed to evenly redistribute the files and maintain a
balanced load across the disks.
• You can increase the speed of a rebalance operation to cause it to finish sooner, or decrease the
speed to reduce the impact on the I/O subsystem. One advantage of ASM is that mirroring is
applied on a file basis, rather than on a volume basis. Therefore, the same disk group can contain
a combination of mirrored or no mirrored files.
• ASM supports data files, log files, control files, archive logs, Recovery Manager (RMAN) backup
sets, and other Oracle database file types.