Thin Provisioning

Thin provisioning is a storage virtualization technology that uses physical storage only when data is written instead of traditional provisioning, which reserves all the capacity up-front when an application is configured. This method addresses over-provisioning and its associated costs. Frequently, volumes reserve excessive space against expected growth. Often this growth does not materialize, or materializes much later than expected. With thin provisioning, you create volumes and assign them to servers and applications, but the physical resources are only assigned when the data is written. Physical storage that is not being used remains available to other volumes. No unnecessary storage is reserved for use by any single application.

For example, like most SANs, your array must support several applications. Projections show that eventually the total storage needed by all applications will reach 3 TB. However, for the first few quarters of the year, these applications should only use about 300 GB. Instead of creating the volumes using the total 3 TB that you expect to need, with thin provisioning you can create three 1 TB volumes, but set the reserve to only 150 GB for each volume. When you factor in compression savings, the applications should not use the full 3 TB until the next purchasing window, minimizing the cost of buying more capacity until it is needed.