EXPERT RESPONSE
Most enterprises look at provisioning storage as a reactive process. It's often done when a new project is started, or a project exceeds the current space allocation, requiring new space to be allocated. The process of provisioning storage is evolving from reactive to proactive as enterprises learn to utilize storage resource management (SRM) tools to understand the storage utilization of users and applications. Using SRM tools it's easy to understand what data is being actively used. One can look at HSM solutions or disk-based secondary storage solutions as a way to supplement their current storage environments. Several of the newer disk-based secondary storage subsystems have become very attractive as they offer fast recovery capabilities and low-cost solutions.
Another topic that is getting hot in the industry is the idea of thin provisioning of storage. This provisioning is based on a relationship between logical and physical storage resources. For example, a user is given a logical container of 25GB. In reality the actual container is physically smaller -- for example, maybe about 5GBs -- that are taken from a larger virtualized storage pool. The user thinks that they have 25GB, but they are actually using only 5GB so that's all that is allocated. Several studies have shown that many users don't use all of the space that has been allocated to them, which means there is a good deal of unused storage space available. Thin provisioning makes use of this research. With thin provisioning, a company can deal with this under-utilization issue and reclaim space into a larger, virtual pool of storage that can be provisioned to applications or other users without impacting the current applications. Thin provisioning requires a storage administrator to closely manage their storage pool and add storage as needed to keep up with growth. It isn't a perfect fit for all environments, but it can serve the needs of specific applications like home directories.
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