SAF-TE is short for SCSI Access Fault Tolerant Enclosure. When a SCSI backplane includes SAF-TE, auto-rebuild of RAID array is performed automatically after replacing a failed drive. This is convenient because you do not have to start the process manually. When a disk fails or is overheated, the SAF-TE controller immediately informs the host, and the chassis generates audible beeps to alert the users about the critical condition. Without SAF-TE, auto-rebuild of RAID array can only occur if a spare disk is presented. Therefore, the max size of the disk array is less since a spare disk is required.