The Question of Latency
The Challenges of a SAN Between Servers and Storage 
Joerg Moellenkamp does the math to demonstrate that latency does indeed matter when there is SAN between your server and your storage. He pits a direct-connected storage-server configuration that uses a 10 meter long cable against a second configuration that uses a director or a switch and two five meter cables.
Tags: , Joerg Moellenkamp, L2ARC, SAN, SSD, ZFS