The New Virtues of Virtualization (continued)
However, it's not yet clear whether virtualization will result in more or less demand for storage. Since storage can be used far more efficiently, Capizzi makes the case that managers will be buying "less hardware, fewer storage arrays, fewer servers." On the other hand, he notes, virtualization "might make it possible to do things that you couldn't do before" -- which would require more storage capacity.
Many SMBs, Capizzi says, were never entirely comfortable with the level of backup they were performing or with their preparedness for disasters. Virtualization now makes it economically feasible for them to seamlessly replicate data to a second site on a daily basis. But new functions like disaster recovery could require more storage capacity than is saved by virtualization's increased efficiency.
NAS' New Appeal
Storage-area network (SAN) and network-attached storage (NAS) technologies will both continue to be used as virtualization becomes more prevalent. Capizzi says that virtualization "doesn't make anything obsolete that's there today."
For the most part, the choice between SAN and NAS is driven by whether an application requests data in files or in blocks. Office applications such as word processing typically store data in discrete files, making NAS structures preferable, while DBMSs typically access data in i/o blocks, giving the edge to SAN storage.
Because of the way its disk drives are accessed, SAN is often selected for complex applications that require intensive disk use and high performance, such as replicating data from numerous servers, and for applications requiring a particularly high level of reliability. NAS gets the nod for simpler applications -- and it comes with a less-expensive price tag. (article continues)
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