Veritas Storage Foundation and Thin Provisioning: Rationale, Configuration and Benefits
Written By Symantec Development: Data centers are increasingly turning to “thin provisioning” to simplify operational tasks and save capital budget. Thin provisioning, also known as dynamic provisioning, creates a virtual disk drive that appears, to applications and servers, much larger than the actual physical storage allotted to it. As applications write to this virtual disk, the storage array automatically allocates more physical storage. The process is transparent to applications and servers. This lets actual storage demand, rather than forecasts (which tend to overestimate), determine how much physical storage is used.
While thin provisioning is transparent to applications and servers, the reverse is not true – the behavior of the applications and the server does impact how ‘thin’ the storage can be. That behavior varies substantially across different vendors. Veritas Storage Foundation provides substantial benefits for companies using or planning to use thin provisioning.
A key advantage of Storage Foundation comes when migrating data from legacy storage to thin provisioning storage. Traditional migration tools copy both data and empty space, resulting in a “thin” provisioning system that uses just as much storage as the legacy system. In contrast, Storage Foundation strips out empty storage as it migrates data from traditional storage to thin provisioned storage. This avoids unnecessary ‘grow’ events on the thin provisioning array.
Due to its thin provisioning-friendly algorithms and architecture, Storage Foundation triggers fewer ‘grow’ events on the storage array than other alternatives. This results in better storage utilization, less allocated but unused storage, and lower costs. Storage Foundation accomplishes this with smart architectural choices, such as just-in-time metadata, compact addressing, and in-place overwrites. And, when files are deleted, Storage Foundation re-uses the space freed by those files before writing to new locations. These techniques reduce the amount of physical storage that the array allocates. Hewlett-Packard’s StorageWorks Division recently published a thin provisioning guide that gave high marks to Storage Foundation’s utilization efficiency when used with HP’s thin provisioning array.
Storage Foundation supports all thin provisioning architectures currently available, including 3PAR, Hitachi, Hewlett-Packard XP, Network Appliance, and Sun. Storage Foundation has the broadest hardware compatibility list on the market, which lets customers standardize on one toolset for their data center to reduce complexity.
When designing a thin provisioning architecture, consider whether your host-based storage tools add to, or subtract from, the benefits of thin provisioning. Choosing the right ones can be the difference between enjoying the savings that thin provisioning offers, and being asked to figure out why the actual savings were less than forecast.
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