What Exactly Is Thin Provisioning?

It is not uncommon that application owners ask for more storage capacity than they really need. Perhaps this is because storage provisioning can be a time-consuming process. Perhaps a large-scale project is starting up that is anticipated to utilize a significant amount of storage over a multi-year time period and the storage is to be purchased up front. In either case, the end result is that the storage utilization drops and viable storage is left unused. This can be expensive.

The thin provisioning solution presents more storage capacity to the hosts than is physically available on the storage system. It fools the host into thinking that the requested amount of storage is actually allocated when it really is not. The solution proposes to utilize significantly less physical capacity and yet meet the capacity needs of the application owners. Almost every major vendor offers some form of thin provisioning solution.

The concept is not new. Just as the vault at your local bank does not contain all the money that is in everyone's account, thin provisioning allows for the allocation of storage resources as they are needed. As long as every application does not demand its promised allocation simultaneously, thin provisioning works well. Thus, careful planning is required to determine which applications are appropriate candidates for thin provisioning and which are not. Usually, applications that either grow at a predictable rate or grow in organized stages tend to be good candidates.