Dot Hill Systems SANnet II 200 FC, Инструкция по установке, эксплуатации и обслуживанию

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5-6 SANnet II 200 FC, SATA, and SATA SE Array Installation, Operation, and Service Manual • March 2005
Note –
Multipathing for FC, SATA, and SATA SE arrays is provided by SANpath
software.
Remember these important rules:
■
A single logical drive can be mapped to only one controller, either the primary
controller or the secondary controller.
■
In a point-to-point configuration, only one host ID per channel is allowed. The host
ID can be assigned to the primary controller and be a PID, or it can be assigned to
the secondary controller and be a SID.
■
If you have two switches and set up multipathing (to keep all logical drive
connections operational for any switch failure or the removal of any I/O controller
module), ensure that each logical drive is mapped to two ports, one on each I/O
controller module, and on two channels. The cables from the two ports mapped to
each logical drive must be cabled to two separate switches. See Figure 5-1 and
Figure 5-2 for examples of this configuration.
The following figures (Figure 5-1 and Figure 5-2) show the channel numbers (0, 1, 4,
and 5) of each host port and the host ID for each channel. N/A means that the port
does not have a second ID assignment. The primary controller is the top I/O controller
module, and the secondary controller is the bottom I/O controller module.
The dashed lines between two ports indicate a port bypass circuit that functions as a
mini-hub. 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.