Oracle Exam 1Z0-414 Topic 1 Question 2 Discussion

By default, a LUN reserves exactly enough space to completely fill the volume. This ensures that clients will not get out-of-space errors at inopportune times. This property allows the volume size to exceed the amount of available space. When set, the LUN will consume only the space that has been written to the LUN. While this allows for thin provisioning of LUNs, most filesystems do not expect to get 'out of space' from underlying devices, and if the share runs out of space, it may cause instability and/or data corruption on clients.