IBM TotalStorage DS4000 EXP700 Installation, User's, And Maintenance Manual page 94

Figure 51 on page 63 shows an example of a fully configured storage server with
the maximum number of drive loops that are supported. Before you cable a new
storage expansion enclosure to a loop, refer to the Fibre Channel Cabling
Instructions that come with your storage server for specific instructions.
To add a storage expansion enclosure to a fibre channel loop, cable the SFP
module input port on an existing ESM (shown as "Last DS4000 EXP700" in
Figure 51 on page 63) to an SFP module output port (shown as "New DS4000
EXP700"). You can cable additional storage expansion enclosures until the loop
reaches the maximum defined by the storage server. The storage server might also
have cabling configuration information or restrictions that you must follow. The
numbers provided in Figure 51 on page 63 indicate the proper cabling order for
adding a new storage expansion enclosure.
Note: Figure 51 on page 63 shows only one example of redundant loop cabling.
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IBM TotalStorage DS4000 EXP700 and EXP710 Storage Expansion Enclosures: Installation, User's, and Maintenance Guide
Important
v Always add a new storage expansion enclosure to the end of a drive loop,
as described in this section.
Exception when intermixing DS4000 EXP700s and DS4000 EXP710s:
Depending on the model of the last storage expansion enclosure in the
existing drive loop and the model of the storage expansion enclosure to be
added, you might not be able to add a new storage expansion enclosure to
the end of a drive loop if you are already intermixing DS4000 EXP700s and
DS4000 EXP710s in the same drive loop. To minimize problems that could
arise during the addition of a new storage expansion enclosure in a
redundant drive loop environment that intermixes DS4000 EXP700s and
DS4000 EXP710s, it is strongly recommended that the addition of new
storage expansion enclosures be performed when the configuration is
offline (all applications have been stopped and the DS4000 configuration
has been powered down). Contact IBM support for help if required.
v If you are intermixing DS4000 EXP700s and DS4000 EXP710s in the same
drive loop, review the requirements discussed in "Intermixing DS4000
EXP700s and DS4000 EXP710s in the same loop" on page 44.
v If you are intermixing FAStT EXP500s and DS4000 EXP700s in the same
drive loop, review the requirements discussed in "Connecting storage
expansion enclosures in a loop with FAStT EXP500s (DS4000 EXP700
only)" on page 50.
Other examples are provided in "Cabling the storage expansion enclosures
in a redundant loop" on page 53.