Hitachi AMS 2100, Hardware Manual

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Hardware components
Hitachi AMS 2100/2300 Storage System Hardware Guide
High-density expansion unit
A high-density expansion storage unit (factory designation RKAKX) provides
significant additional storage capabilities for the base units. It contains from
4 to 48 SATA disk drives, four redundant power supplies, and four ENC
adapter units (cards). The ENC units manage the drives and are also used
to connect the expansion unit to the base unit, expansion units, and other
expansion units. See Disk drive configurations in this chapter and RAID
implementations on page 1-22 for detailed information about the number
and type of disk drives that can be installed in an expansion unit.
There are no switches on a high-density expansion unit. Power is turned on
and off with a control signal that is routed from the base unit via the ENC
cables that are connected to the ENC unit in the high-density expansion
unit.
Both the AMS 2100 and the AMS 2300 base units use the same high-density
expansion unit. They each support only one high-density expansion unit.
High-density expansion unit front view
Figure 4-29 shows the front of a high-density expansion unit with the
decorative front bezel installed.
The front panel of the high-density expansion unit includes two sets of
Power and Locate status LEDs that show the status of each section (A and
B) in the unit and identify the unit in case of a failure. The installation
location should provide an unobstructed view of these LEDs.
Figure 4-29: High-density Expansion Unit Front View
NOTE: Disk drives are installed, removed, and replaced from the top of
the high-density expansion unit. No tools are required, but the cover over
the drives is locked and must be unlocked from the key on the front panel
of the unit (see Figure 4-30 ).