The SUN StorageTek 6540 is a 4Gbps Fibre Channel SAN solution. The controller tray features (2) high performance RAID controllers, each with (4) 4Gb/s host ports and (4) 4Gb/s drive expansion ports. Up to 8GB of cache may be installed per controller.
Capacity can be added to the 6540 controllers via CSM200 (CSMII) expansion enclosures which offer (16) drive slots. Up to (14) CSM200-EU expansion trays can be attached to the controller in an optional expansion cabinet for a total support of 224 drives.
Note that enclosures have a 2Gb / 4Gb link rate switch on the front. All 10K RPM FC disk drives operate at 2Gbps and must be installed in enclosures that have link rate switch set to 2Gbps. All SUN qualified 15K FC and SATA disk drives for the 6140 controller can negotiate at 4Gbps and should be installed in enclosures with the link rate switch set to 4Gbps. 4Gbps capable drives can revert to 2Gbps FC operation, but this configuration is not recommended.