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SAN speed and server accommodation

I'm a student at Prince George's Community College and I want to know what the top speed is for a SAN and how many servers can a SAN accommodate at one time.

Today, the current shipping speed for a Fibre Channel-based SAN products is 2-gigabits per port that is 200 MB per second. Max throughput after overhead is a bit less, and depends on the Host Bus Adapter, switch, OS and driver used. 4-gigabit and 10-gigabit connections are on the horizon.

The maximum connectivity is around 239 switches (domains) although I have yet to see a single fabric that large. Most large SANs are broken down into smaller physical or virtual, if the switch supports it) fabrics. The switches can be smaller 16-port switches or director class switches that can have over 200 ports each. You can do the math on max connectivity from there. It's in the thousands but for traffic and error isolation, fewer connections should be used. Sixteen switches in a single fabric seems to be a good rule of thumb. Using a core edge design, you can add more switches and still keep the hop count quite low especially when director class switches are used as the core.


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