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Cluster : Storage > Aggregates : Understanding aggregates : About thin provisioning
About thin provisioning
Using thin provisioning, you can appear to provide more storage than is actually available from a given aggregate, as long as not all of that storage is currently being used. Thin provisioning is also called aggregate overcommitment.
The storage provided by the aggregate is used up only as reserved LUNs are created or data is appended to files in the volumes.
Note: The aggregate must provide enough free space to hold the metadata for each FlexVol volume it contains. The space required for a FlexVol volume's metadata is approximately 0.5 percent of the volume's configured size.
When the aggregate is overcommitted, it is possible for writes (hole writes or overwrites) to LUNs or files in volumes contained by that aggregate to fail if there is not sufficient free space available to accommodate the write.
You can configure a thinly-provisioned volume to automatically secure more space from its aggregate when it needs to. However, if you have overcommitted your aggregate, you must monitor your available space and add storage to the aggregate as needed to avoid write errors due to insufficient space.
Aggregates can provide storage to volumes contained by more than one Vserver. If you are using thin provisioning and you need to maintain strict separation between your Vservers (for example, if you are providing storage in a multi-tenancy environment), you should either use fully allocated volumes (thick provisioning) or ensure that your aggregates are not shared between tenants.
For more information about thin provisioning, see Technical Reports 3563 and 3483.
Related Link:  
TR-3563: NetApp Thin Provisioning
TR 3483: Thin Provisioning in a NetApp SAN or IP SAN Enterprise Environment

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