Which two statements are true about variable extent size support for large ASM files?
A.
The metadata used to track extents in SGA is reduced.
B.
Rebalance operations are completed faster than with a fixed extent size
C.
An ASM Instance automatically allocates an appropriate extent size.
D.
Resync operations are completed faster when a disk comes online after being taken offline.E. Performance improves in a stretch cluster configuration by reading from a local copy of an extent.
Explanation:
A: Variable size extents enable support for larger ASM datafiles, reduce SGA memory requirements for very
large databases (A), and improve performance for file create and open operations.
C: You don’t have to worry about the sizes; the ASM instance automatically allocates the appropriate extent
size.
Note:
* The contents of ASM files are stored in a disk group as a set, or collection, of data extents that are stored on
individual disks within disk groups. Each extent resides on an individual disk. Extents consist of one or more
allocation units (AU). To accommodate increasingly larger files, ASM uses variable size extents.
* The size of the extent map that defines a file can be smaller by a factor of 8 and 64 depending on the file size.
The initial extent size is equal to the allocation unit size and it increases by a factor of 8 and 64 at predefined
thresholds. This feature is automatic for newly created and resized datafiles when the disk group compatibility
attributes are set to Oracle Release 11 or higher.