Storage area networking Virtualization Guidelines

SAN Virtualization Guidelines

Now that SAN "implementations" has matured with an ample collection of Fibre Channel products, it's time to turn our attention to fully harnessing the storage assets at the other end of the light beams. That takes us to SAN virtualization.

While SAN connections widen the pipes and stretch the distance between disks and hosts, the new plumbing alone does little to reconcile the conflicts among servers competing for scarce disk space. You can look at SAN virtualization products as capacity brokers in this chaotic environment. In their simplest form, they collect all or portions of the SAN's physical disks into a pool, and hand out logical slices to needy application servers without having to re-cable or rezone the SAN.
Properly architected, virtualization provides many benefits, such as the ability to allocate storage resources on-demand, integrate storage products from multiple vendors, configure selectively for high availability and reduce the total cost of ownership. Choosing a virtualization product is the challenge. We'll give you some guidelines that our customers use, and consequently, influence our solutions.

Virtualization Schemes
Five divergent approaches to sharing virtual disk capacity have emerged in the SAN market, spanning about 10 discrete implementations. Ranging broadly in price, performance, and utility, these virtualization solutions can be categorized by the methods they use to translate the the physical reality to the host's logical view. The effectiveness of each technique is essentially determined by where in the SAN the mapping takes place and what platform is used to deliver the services.The offerings are:
* Multi-host storage arrays
* Host-based LUN masking filters
* File system redirectors via outboard metadata controllers
* Specialized in-band virtualization engines
* Dedicated storage domain servers