Exp400 Expansion Unit - IBM TotalStorage DS300 Best Practices Manual

3.5 EXP400 expansion unit

Up to two EXP400 expansion units can be attached to an IBM DS400 subsystem
for a total of 40 hard disk drives.
The EXP400 Storage Expansion Unit supports up to 14 LVD (low voltage
differential) Ultra320 SCSI disk drives which transfer data at 320MB/s. The
EXP400 supports SCSI drives on a single or dual bus. It supports a cable
distance of up to 20 meters.
The EXP400 delivers fast, high-volume data transfer, retrieval, and storage
functions across multiple drives. The modular, redundant disk drives, power
supply with fan units, and SCSI Bus Expander and Enclosure Services Module
(ESM) use hot-swap technology for easy replacement without turning off the
expansion unit.
Figure 3-15 EXP400 front view
The EXP400 accepts only slim-high Ultra320 SCSI drives. These drives must be
in the same Ultra320 tray that is supported in the IBM Ultra320 servers. Ultra320
SCSI drives up to 300GB's in size can be installed in the EXP400 which give it
the ability to support up to 4TB's of storage capacity. The unit supports either 10k
RPM or 15k RPM SCSI disk drives. To activate the Blue Box Identity LED,
ServeRAID Manager must be used. The amber general fault LED is activated by
any fault that occurs in the enclosure.
Figure 3-16 on page 53 displays a rear view of the EXP400 and the position of
the two Enclosure Services Module (ESM) boards. An ESM provides the SCSI
interface to the hard disk drives and monitors the overall status of the expansion
unit. Each EXP400 supports up to two ESMs.
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IBM TotalStorage DS300 and DS400 Best Practices Guide