1. Do not connect a combination of more than six EXP520 or EXP810 storage
expansion enclosures to the two ports of a dual-ported drive channel. Failure
to observe this limitation might result in loss of data availability. In the DS5020
storage subsystem environment, no more than six EXP520 or EXP810 storage
expansion enclosures can be connected to the two ports of a dual-ported drive
channel because of the internal drive slots in the DS5020 storage subsystem.
2. Do not connect more than four EXP520 or EXP810 storage expansion
enclosures to each port of a dual-ported drive channel.
3. Add storage expansion enclosures to the storage subsystem drive ports in a
round-robin fashion. For example, if you have four drive expansion enclosures
to be cabled to the storage subsystem, instead of cabling all four drive
expansion enclosures to one drive port of a drive channel, distribute the
enclosures to all drive ports, which results in one enclosure per drive port of a
drive channel.
4. Do not connect more than the maximum number of enclosures per drive
channel, which is eight for EXP520s and EXP810s.
5. The DS5020 storage subsystem supports the connection of a maximum of six
storage expansion enclosures per redundant drive channel loop and supports
one redundant drive channel loop pair. Failure to observe this limitation might
result in loss of data availability.
6. The DS5020 currently supports a maximum of 112 drives in six 16-drive
storage expansion enclosures per drive channel in each controller. One drive
channel from each of controllers Aand B must be connected to the same set
of storage expansion enclosures to provide drive channel redundancy. Do not
connect a combination of more than six storage expansion enclosures to the
two ports of a single drive channel.
7. When connecting six storage expansion enclosures to a DS5020, use all ports
in both drive channels. See Figure 42 on page 64 for the cabling topology.
8. Connect a maximum of four EXP520s or EXP810s per DS5020 controller drive
port.
9. When mixing different types of storage expansion enclosures in the same drive
channel pair, the link rate Setting must be the same for each storage
expansion enclosure. IBM does not support different enclosure speed settings
in the same drive channel.
10. The controller drive ports of the DS5020 storage subsystem controllers must
always be connected to ports labeled 1B in both the right and left ESMs of the
EXP810s in the redundant drive channel/loop pair that is connected to the
DS5020 storage subsystem. Figure 45 on page 69 shows the location of the
ports.
11. Toattach EXP810 storage expansion enclosures to the DS5020, you must
purchase the Attach EXP810 to DS5020Activation feature option. Contact your
IBM marketing representative for more information.
12. Toattach 33 - 64 additional drives to the DS5020, you must purchase the
DS5020 Drive Attach 33 - 64 feature option. Toattach 65 - 112 additional
drives to the DS5020. you must purchase the DS5020 Drive Attach 65- 112
feature option in addition to the DS5020 Drive Attach 33 - 64 feature option.
Contact your IBM marketing representative for more information.
68 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide