Abstract: An apparatus and a method facilitate the sharing of a SCSI address ID between a SCSI initiator and a target device. The SCSI standard does not prohibit ID sharing under a set of operating conditions defined by this invention. The shared ID is preferably used for controlling an environmental monitor device that controls the power of disk drives on the SCSI bus, detects their status and configuration, and monitors environmental conditions within a mass storage system cabinet. Power to individual disk drives is switched under control of the computer operating system so that start-up surge current to the disk drives is limited. This allows defective drives to be powered down and replaced without powering down the remaining good drives. SCSI termination power distribution is improved so that connector reversals can be detected and resulting current surges limited. Termination power control and status is under program control.