Solution:

This LED shows SCSI drive channel on LVD or Single-End mode. On each SCSI drive channel of RAID 500, there is two terminators available. One is built-in SCSI cable, in which the LEDs have been removed. And the other one is on rear panel of RAID 500, an external type. By LED status of external terminator, the SCSI bus mode is presented clearly. The relationship of SCSI bus mode and LED color is listed below: Red LED: Single End Active Negation Green LED: LVD