NetApp
Cluster : Storage > Aggregates : Understanding aggregates : Understanding 64-bit and 32-bit aggregates
Understanding 64-bit and 32-bit aggregates
Aggregates are either 64-bit or 32-bit format. 64-bit aggregates have much larger size limits than 32-bit aggregates. 64-bit and 32-bit aggregates can coexist on the same storage system or cluster. They interoperate for some Data ONTAP features but not all.
32-bit aggregates have a maximum size of 16 TB; 64-bit aggregates have a maximum size of up to 100 TB, depending on the storage system model. For the maximum 64-bit aggregate size of your storage system model, see the System Configuration Guide.
You decide the format of an aggregate when you create it. By default, newly created aggregates are 64-bit.
You can upgrade 32-bit aggregates to 64-bit aggregates by increasing their size beyond 16 TB. 64-bit aggregates, including aggregates that were previously upgraded, cannot be converted to 32-bit aggregates.
Related Link:  
System Configuration Guide: now.netapp.com/NOW/knowledge/docs/hardware/NetApp/syscfg/