Acer AcerAltos 19000 User Manual page 173

There are two SCSI backplane boards standard in the AcerAltos 19000. The SCSI
backplane boards provide a convenient interface between the SCSI drives and the
system board. Each board includes seven SCSI drive slots to accommodate the
drive trays, two SCSI channels to connect to the system board and/or SCSI
controller board(s), and one SCSI channel out for external devices.
Each backplane board has the following major features:
"Hot-swap" feature that allows replacement of a defective hard drive even
while the system is in full operation. This feature requires a RAID controller
board and RAID drivers.
Indicates hard disk drive failure through a front panel board LED
Supports wide SCSI disk drives
Each backplane board can be configured as 'split' (2-channels) (default) or
combined into a single SCSI channel
SCSI ID strapping that allows wide SCSI HDD ID configuration through the
backplane instead of configuring individual drive IDs