IBM DS4700 EXPRESS, Installation, User'S, And Maintenance Manual

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For examples of redundant, partially-redundant, and non-redundant host and drive
loop configurations, see “Fibre channel host loop configurations.”
Fibre channel connections
The storage subsystem fibre channel connection consists of up to four host
fibre-channel loops and a redundant drive fibre-channel loop. The host fibre-channel
loops provide the fibre path for host attachment. They can consist of fibre-channel
cables, SFPs, host bus adapters, fibre-channel switches, and RAID controllers. The
redundant drive fibre-channel loop provides the fibre path from the DS4700 Express
Storage Subsystem to the hard disk drives (HDDs) in the storage expansion
enclosures. The redundant drive fibre-channel loop consists of the DS4700 Express
Storage Subsystem, the storage expansion enclosures, fibre-channel cables, and
SFPs.
The DS4700 Express supports redundant drive channel loop configurations. You
can build a redundant drive channel loop by connecting one or more storage
expansion enclosures to the redundant RAID controllers. Then, use dual fiber-optic
cables to connect one storage expansion enclosure to another in a daisy-chain. For
more information, see “Connecting storage expansion enclosures to the DS4700
Express” on page 68.
Fibre channel host loop configurations
You must determine how the host systems will connect to the storage subsystem.
You can connect up to four host systems directly to the storage subsystem, or you
can connect more than two hosts to the fibre channel storage subsystem through
switches. The illustrations in the following sections show common host system
configurations.
Host 1, Host Adapter 1 and 2
Host 4, Host Adapter 1 and 2
Host 2, Host Adapter 1 and 2 Host 3, Host Adapter 1 and 2
ds470024
1 2 3 4
1 2 3 4
Figure 86. Cabling diagram for four redundant host connections
Chapter 3. Cabling the storage subsystem
107