9
Step 6
Verify Storage System Back-End Connections
Use the information below and the diagram to verify the enclosure address settings
and loop (bus) cabling for the SPE and your DAEs.
Each CX700 storage processor has four back-end (BE) ports that connect to the
corresponding primary (PRI) ports on the first DAE (DAE2 or DAE2P) in each loop.
The DAE expansion (EXP) ports connect to the next PRI ports in their loops. The
CX700 supports four redundant loops: 0, 1, 2, and 3 from SP A, and 0, 1, 2, and 3 from
SP B. (Note that some documentation refers to a Fibre Channel loop pair as a
bus
.)
For the system to boot and operate, the first DAE — connected to BE 0 on both SPs —
must have enclosure address (EA) 0. A DAE with boot disks and the CX700
operating system is always assigned enclosure address 0 prior to shipment.
Each DAE
in a loop
requires a unique enclosure address (EA). The first DAE has an
EA of 0, since it is the first EA on the loop (loop 0). A second DAE (the first on loop 1)
also has an EA of 0; a DAE connected to BE 2 or BE 3 is also EA 0 on that loop.
Numbering sequentially, the second EA on each loop is 1, the third 2, the fourth 3,
and so on. Always optimize your storage system by using every available loop, and
spreading the DAEs as evenly as possible across the loops. In an evenly balanced
system that includes both DAE2s and DAE2Ps, segregate the point-to-point
enclosures on discrete loops whenever possible.
The following figure includes DAE2Ps as the only disk-array enclosures. DAE2 and DAE2P
enclosures follow the same EA, loop balancing, and cabling conventions.