Rackable Systems OmniStor 4900F Series, User Manual, Page: 44 / 196

Chapter 2 - Topologies and Operating Modes
Duplex Mode
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Duplex Mode
The duplex operating mode is a dual RAID controller solution providing a redundant
controller or an active-active RAID storage solution. Beginning with a minimum level
redundancy solution it can be configured to provide the most robust redundant RAID
storage solution. This operating mode supports the Multiple Port Mirrored topology.
In a Multi-Port topology, all ports are active and provide transparent hardware failover and
failback operations. It provides for higher host bandwidth capabilities with each port
connected to an individual fibre loop.
During controller failure, internal HUB circuitry on the Host I/O cards automatically
detect a failure and connects the incoming Fibre loops together so that the surviving
controller immediately starts processing host commands.
There are essentially five supported topologies available for the Duplex mode:
n
“Multi-Port Mirrored Single Host-Single Connection” on page 31.
n
“Multi-Port Mirrored Single Host-Dual Connection” on page 32.
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“Multi-Port Mirrored Dual Host System-Quad Connection” on page 35.
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“Multi-Port Mirrored SAN Attach Single Switch Connection” on page 36.
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“Multi-Port Mirrored SAN Attach Dual Switch Connection” on page 37.
NOTE:
Some Operating Systems, such as HP-UX, when connected to a fabric require
that you set the Controller Parameter option “Host Different Node Name” to
enabled. This will cause the controller to present a different Configuration WWN
for each controller port. Otherwise if the same WWN is reported on both ports,
one port would be blocked by the OS. Refer to the VT-100 or StorView Software
Guide for specific information on this option.