Post by Keith Schultz (thank you)
When it comes to making virtual server farms easier to manage, the SAN is the great enabler. But when it comes to maximizing virtual server performance, the SAN is the great bottleneck. A single host running dozens of virtual machines (or more) can easily generate enough I/O operations to reduce overall SAN response time, increasing I/O latency and adversely affecting virtual machine performance. Adding more spindles may help in the short term, but that can be very disruptive to the storage infrastructure and does not really take care of the root of the problem: I/O bottlenecks.
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