Disappointed In Thin?

In a recent review of Symantec's 2009 Stop Buying Storage Survey, an odd result on thin provisioning might get overlooked. 42% of users are essentially disappointed in their thin provisioning investment, and another 37% only indicated seeing moderate improvement. If you aren't in the small group that saw significant improvement, you may have invested in the wrong thin provisioning technology.Symantec commissioned this survey through Applied Research in March 2009 with a total of 400 IT professional respondents from the United States with direct responsibility over or within their organization's storage infrastructure and operations. The 2009 Stop Buying Storage survey highlights storage utilization trends and other storage-related habits related to the optimization of current storage capacity.

Based on experience the 22% that saw significant improvement should be closer to 100%. What keeps many organizations from seeing significant improvement generally centers on two areas that have plagued some thin provisioning implementations; conversion to thin and reclamation.

Conversion to thin provisioning as we detail in our article "Converting from Fat Volumes to Thin Provisioning" is one of the first challenges that a company will face when implementing a storage system that can perform thin provisioning. The problem is that if you use a standard migration utility, which you almost have to do to get the conversion done quickly, it copies data over via the SAN with a block by block copy. While the performance of this type of migration is excellent it is not exactly very smart. Free space and data that has been deleted but not removed from disk get copied over as well.

The second issue that has plagued thin provisioning is that during use, deleted items do not properly get reclaimed. This is because most file systems do not really delete data when you give the delete command, they just set the data as eligible to over write. If you go through a big house cleaning operation on a volume, that freed up space is not reallocated to the global storage pool that thin provisioning storage systems count on. It stays with the volume.

The result of these two factors is that thin provisioned systems put on a little weight both initially and over time. While some thin provisioning is better than no thin provisioning these challenges lead to the poor results on the survey. Companies like Symantec, 3PAR, HDS and DataCore have all announced technologies that can address both the conversion to thin issues as well as the ongoing space reclamation issues.

With these technologies companies can intelligently convert to thin to see immediate storage savings and can keep their volumes thin over time. Thin provisioning is more than a check mark feature, it is a serious technology that when all the challenges are properly addressed can save significant storage costs in the enterprise.

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George Crump is founder of Storage Switzerland, an analyst firm focused on the virtualization and storage marketplaces. It provides strategic consulting and analysis to storage users, suppliers, and integrators. An industry veteran of more than 25 years, Crump has held engineering and sales positions at various IT industry manufacturers and integrators. Prior to Storage Switzerland, he was CTO at one of the nation's largest integrators.