The figure shows the ASM file extent relationship with allocation units. Extent size is always equal to the AU up to the first 2000 extents. The figure shows the first eight extents distributed on four ASM disks. The extent size becomes 8*AU. This appears as bold rectangles labeled with the extent numbers 20,001 to 20,007, and so on. The next increment for an ASM extent is 64*AU which is not shown in the figure. The ASM coarse striping is always equal to the disk group AU size, but the fine striping always remains 128KB in any configuration (not shown on graph). The ASM extent map memory overhead is reduced by approximately a factor of 1/8 or 1/64 depending on the size of the ASM file.