Thin Provisioning

Thin provisioning[1] is a mechanism that applies to large-scale centralized computer disk storage systems, SANs, and storage virtualization systems. Thin provisioning allows space to be easily allocated to servers, on a just-enough and just-in-time basis.

Contents [hide] 1 Overview 1.1 Over-allocation 2 Notes 3 See also

[edit] Overview Thin Provisioning, in a shared storage environment, is a method for optimizing utilization of available storage. It relies on on-demand allocation of blocks of data versus the traditional method of allocating all the blocks up front. This methodology eliminates almost all whitespace which helps avoid the poor utilization rates, often as low as 10%, that occur in the traditional storage allocation method where large pools of storage capacity are allocated to individual servers but remain unused (not written to). This traditional model is often called "fat" or "thick" provisioning.

With thin provisioning, storage capacity utilization efficiency can be automatically driven up towards 100% with very little administrative overhead. Organizations can purchase less storage capacity up front, defer storage capacity upgrades in line with actual business usage, and save the operating costs (electricity and floorspace) associated with keeping unused disk capacity spinning.

Previous systems generally required large amounts of storage to be physically preallocated because of the complexity and impact of growing volume (LUN) space. Thin provisioning enables over-allocation or over-subscription.

Thin Provisioning was first introduced to the storage community in February 2002 as "Network Managed Volumes" in DataCore Software's SANsymphony Storage Virtualization platform. Later that same year, 3PAR Inc. introduced the feature and coined the term Thin Provisioning. StarWind Software has TP as part of their iSCSI target for years.

[edit] Over-allocation