Storage area networks (SANs) have greatly simplified the management of storage resources. By creating a centralized storage pool that can be allocated as needed, SANs have enabled many organizations to reduce both management and capital costs. Now, an approach has emerged to take SANs to the next level, with further simplification and savings. It's called thin provisioning.
Thin provisioning helps IT departments attack the fundamental problem of storage under-utilization. In many businesses, a significant portion of purchased storage is not in active use, although it is kept constantly available — taking up real estate in the data center, consuming power, and increasing the load on data center cooling equipment. In addition to wasting opex dollars, there is a capex penalty to this approach. By buying storage capacity "too soon," IT organizations fail to benefit from the constantly falling cost per GB that each new generation of storage technology provides.
In essence, thin provisioning changes the process of allocating space on a SAN so that physical storage resources are only committed to a volume when data is actually written to it, eliminating significant waste.
Currently, to allocate space on a SAN, an IT administrator defines a logical volume and makes it available to a server. The SAN controller then responds by reserving physical space on the array of disk drives that it manages. Every byte of storage determined by the volume size is backed up with a physical location, whether it is used or not.
With this approach, unused space is effectively wasted, because it cannot be reclaimed for other volumes or applications. With thin provisioning, this space is available, because each volume claims physical resources only when needed. Furthermore, the allocation process is automated, so that administrators don't have to spend extra time.
The net result is that IT organizations can come much closer to the goal of purchasing storage when it's actually needed, while reducing the complexity of the administration process.
You can find more detail in my recently published article in Dell Power Solutions.