It All Adds Up to ISLs, Mesh Networks
Simple math shows why 10G-BPS Fibre Channel speed matters a great deal for Inter-Switch Links.
To establish a 10G-bps link between two switches using standard 2G-bps Fibre Channel ports, an IT manager would have to dedicate five ports on each switch to generate an ISL trunk between them. On a small, entry-class switch such as QLogic Corp.s SANbox 5200, which has only 16 2G-bps ports to start with, doing so would consume nearly a third of the switchs ports just to set up a single ISL trunk.
Now imagine having to add a third switch to the mesh of this SAN (storage area network). In this scenario, the IT manager would need an extra five ports on each switch to complete the mesh, which would leave just six ports on each switch to hook in targets (storage devices) and initiators (servers and workstations).
By using the 10G-bps ISLs on the SANbox 5200 (four 10G-bps ports per switch), an IT manager can easily create a five-switch mesh network without using any 2G-bps Fibre Channel switch ports. This would allow managers to slowly expand their SAN projects simply by stacking more SAN switches to satisfy their need for higher port counts.
With 10G-bps ISL ports, QLogics SANbox 5200 Fibre Channel switch is a capable unit for deploying a group of shared storage resources. For example, an IT manager can use the SANbox 5200 to link 16 libraries and tape drives on the 2G-bps Fibre Channel ports and use the ISL ports to hook to switches with servers attached to them.
Using the SANbox 5200s zone management software on the ISLs, IT managers control which servers have access to the storage resources at any given time. This should make storage resource sharing an easier chore.