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Enterprise applications which use up the maximum amount of physical storage capacity allotted to them at best suffer from a decrease in performance or at worst crash completely. Therefore, IT administrators must ensure that they have enough unused capacity to meet expected future requirements.
However, when multiple applications are each allocated extra capacity, the result is a severe underutilization of a storage array's or a SAN's total capacity, forcing businesses to purchase more storage capacity than actually needed.
Thin provisioning, which is a feature of most major storage arrays, helps eliminate that underutilization by causing applications to think they have more capacity than needed without actually allocating that capacity until it is required. It relies on the ability of a storage array to automatically grab more physical capacity from a pool of unused disk space and re-assign it to an application as it is needed rather than assigning large amounts of physical capacity to the application.
The ability to better manage growing storage capacity is a critical need for businesses.
IDC, in its fifth annual survey on the state of the digital data universe, said in June that the amount of data being stored is more than doubling every two years, and could grow by 50 times by 2020.
In the survey, IDC found that the amount of data created and replicated is expected to top 1.8 zettabytes, or 1.8 billion TBs, in 2011, up from just over 1 zettabyte in 2010.
IDC also reported that 75 percent of the information being created today is coming from individuals who write text, take photos, or upload videos and music, and that information about such individuals is actually growing faster than data created by them. However, IDC said, enterprises will at some point be responsible for some part of the liability of 80 percent of that data.
Thin provisioning has a couple of advantages compared to traditional storage provisioning.
The primary advantage is a lower cost for storage. With traditional provisioning, an IT manager would have to purchase and deploy excess capacity for multiple applications separately. With thin provisioning, all the excess capacity sits in a single pool that is available to those multiple applications as needed regardless of how much capacity each application thinks it can access. However, since the various applications will require additional capacity at uneven rates, the total amount of physical capacity needed will be less than the total sum of the individual physical capacity of each application under traditional provisioning.
In addition to the lower capacity requirements needed under thin provisioning, another advantage lies in the fact that the per-GB cost of storage typically falls over time. As a result, purchasing smaller amounts of capacity in several stages while prices drop cuts the cost of storage compared to purchasing it in larger lump sums.
The other advantage of thin provisioning is increased management flexibility. With thin provisioning, IT administrators will be required to physically add capacity based on the overall storage requirements, whereas with traditional provisioning there may be more work involved in maintaining the capacity requirements of multiple applications.
Thin provisioning technology typically sends alerts when the capacity used reaches a certain threshold, such as 90 percent of provisioned capacity, giving administrators the opportunity to allocate more disk space to the application.