This document explains how to resize the grid disks in Exadata (to make them larger), when there is free space in the cell disks. The free space can be anywhere on the cell disks. In other words, the grid disks can be built from and extended with the non-contiguous free space.
Typically, there is no free space in Exadata cell disks, in which case the MOS Doc ID 1465230.1 needs to be followed. But (more...)