5-12 Sun StorEdge 3000 Family Installation, Operation, and Service Manual • May 2004
■ The port bypass circuit on each channel connects the upper and lower ports on
the same channel and provides access to both controllers at the same time.
■ If there are two host connections to the upper and lower ports on Channel 0,
and one host connection is removed, the other host connection remains
operational.
■ Therefore, if you have a redundant multipathing configuration in which you
have two host connections to each logical drive and one connection fails, the
remaining path maintains a connection to the logical drive.
In
FIGURE 5-1 and FIGURE 5-2, with multipathing software to reroute the data paths,
each logical drive remains fully operational when the following conditions occur:
■ One switch fails or is disconnected, and the logical drive is routed to the second
switch. For example, if switch 0 fails, switch 1 automatically accesses logical drive
0 through the cabling to the lower port on PID 41.
■ One I/O controller module fails, and all the host IDs for that controller are
reassigned (moved) to the second 1/O controller module. For example, if the
upper I/O controller module is removed, host IDs 40 and 41 are automatically
moved to the lower module and are managed by the second controller.
■ An I/O controller module fails or one cable is removed from an I/O controller
module, and all I/O traffic to the disconnected channel is rerouted through the
second port/host LUN assigned to the logical drive. For example, if you remove
the cable to channel 4, the data path for logical drive 1 switches to the port on
channel 5.
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