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Installing the DuraStor Storage Subsystem
access is provided to the individual active ports of each RAID
controller. See
Active-Active Dual-Port, Hubs Disabled on page 3-40
Use active-active dual-port mode with the internal hubs enabled
when one or two hosts needs to be connected to the storage
subsystem. This mode eliminates the need for external switches/
hubs and still provides a fault-tolerant environment. See
Active-
Active Dual-Port, Hubs Enabled on page
3-42.
Active-Active Single-Port Topology
Use active-active single-port mode when you have an application
that requires a high-performance, robust, full system-level fault-
tolerant disk storage solution and transparent controller failover.
This dual controller configuration supports hosts with a single
Fibre Channel port. It is very similar to the active-active dual-port
configuration, except that only two of the four ports are passive.
This configuration is ideal when the host driver software will not
support LUN zoning, as would be the case in active-active dual-
port mode.
Use active-active single-port mode with the internal hubs disabled
when the application requires an external switch/hub. This mode
is generally used when four or more hosts are required. Single loop
access is provided to the individual ports of each RAID controller.
See
Active-Active Single-Port, Hubs Disabled on page
3-43.
Use active-active single-port mode with the internal hubs enabled
when one or two hosts need to be connected to the storage
subsystem. This mode eliminates the need for external hubs or
switches and still provides a fault-tolerant environment. See
Active-
Active Single-Port, Hubs Enabled on page
3-44.
About Stand-Alone Mode
In Stand-Alone mode, the Fibre Channel-to-SCSI RAID controller
operates autonomously. In dual-host port operation, there are up to
four disk channels.
One advantage of running dual-host port mode is to maximize
bandwidth and host IOPs. For sequential access patterns, where
disks can supply more than 160 MB/sec of data to a host, it could
be advantageous to run in dual-port mode.
3-35
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