IBM System Storage Subsystem DS5020 - Manual (Page 38)

Using non-supported E-DDM options or FRUs will result in the E-DDM being locked
out by the DS5020 controller firmware and might also damage the drive connector
in the enclosure midplane.
Attention:
1. After you remove an E-DDM CRU, wait 70 seconds before replacing or
reseating the E-DDM CRU to allow it to properly spin down. Failure to do so
might cause undesired events.
2. Never hot-swap an E-DDM CRU when its associated green Activity LED is
flashing. Hot-swap an E-DDM CRU only when its associated amber Fault LED
lights is not flashing or when the E-DDM is inactive and its associated green
Activity LED lights is not flashing.
Note: If the E-DDM you want to remove is not in a failed or bypass state, always
use the Storage Manager client program either to place it in a failed state or
to place the array that is associated with the E-DDM (or E-DDMs) in an
offline state before you remove it from the enclosure.
Controllers
The DS5020 has two hot-swappable and redundant RAID controllers. The
controllers are located at the back of the storage subsystem. The left controller is
labeled controller A, and the right controller is labeled controller B. One controller
will continue to operate if the other controller fails.
The controllers contain the storage subsystem control logic, interface ports, and
LEDs. Depending on the DS5020 configuration you purchased, your controllers are
one of the following types:
v Controllers with 1 GB memory, two standard 8 Gbps FC host ports, and two
standard 4 Gbps FC drive channel ports
v Controllers with 1 GB memory, two standard 8 Gbps FC host ports, one optional
2-port 8 Gbps FC host card, and two standard 4 Gbps FC drive channel ports
v Controllers with 1 GB memory, two standard 8 Gbps FC host ports, one optional
2-port 1 GB iSCSI host card, and two standard 4 Gbps FC drive channel ports
v Controllers with 2 GB memory, two standard 8 Gbps FC host ports, and two
standard 4 Gbps FC drive channel ports
v Controllers with 2 GB memory, two standard 8 Gbps FC host ports, one optional
2-port 8 Gbps FC host card, and two standard 4 Gbps FC drive channel ports
v Controllers with 2 GB memory, two standard 8 Gbps FC host ports, one optional
2-port 1 GB iSCSI host card, and two standard 4 Gbps FC drive channel ports
Each controller for the DS5020 has Fibre Channel or iSCSI drive ports for
connecting to the storage expansion enclosures and two Ethernet ports for DS5020
subsystem management. See Figure 2 on page 10, Figure 3 on page 10, or
Figure 4 on page 10.
The iSCSI ports support both IPv4 and IPv6 TCP/IP addresses, CHAP, and iSNS.
Use either Cat5E or Cat6 Ethernet cable types for iSCSI port connections. A Cat6
Ethernet cable provides optimal performance.
Although both controllers (A and B) are identical, they are seated in the DS5020
chassis in opposite orientations. If the controller cannot fully be inserted in the
controller bay, flip it 180 degrees and reinsert it. Do not force fit because it might
cause damage to the controller unit.
8 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide