With thin provisioning, when you create volumes and LUNs in a given aggregate, you do not actually allocate any space for those in advance. The space is allocated as data is written to the volumes or LUNs.
The unused aggregate space is available to other volumes and LUNs. By allowing as-needed provisioning and space reclamation, thin provisioning can improve storage utilization and decrease storage costs.
A FlexVol volume can share its containing aggregate with other FlexVol volumes. Therefore, a single aggregate is the shared source of all the storage used by the FlexVol volumes it contains. Flexible volumes are no longer bound by the limitations of the disks on which they reside. A FlexVol volume can be sized based on how much data you want to store in it, rather than on the size of your disk. This flexibility enables you to maximize the performance and capacity utilization of the storage systems. Because FlexVol volumes can access all available physical storage in the system, improvements in storage utilization are possible.
With thin provisioning, the storage administrator provisions 500 GB to the business application but uses only 100 GB for the data. The difference is that with thin provisioning, the unused 400 GB is still available to other applications. This approach allows the application to grow transparently, and the physical storage is fully allocated only when the application needs it. The rest of the storage remains in the free pool to be used as needed.