5-10 Sun StorEdge 3000 Family Installation, Operation, and Service Manual • May 2004
Caution – In point-to-point mode or in public loop mode, only one switch port is
allowed per channel. Connecting more than one port per channel to a switch can
violate the point-to-point topology of the channel, force two switch ports to “fight”
over an AL_PA (arbitrated loop physical address) value of 0 (which is reserved for
loop to fabric attachment), or both.
■ With four host channels and four host IDs, you should load-balance the host ID
setup so that half the IDs are on the primary controller and half the IDs are on the
secondary controller. When setting up LUNs, map each LUN to either two PIDs
or two SIDs. The hosts are in turn dual-pathed to the same two switched fabrics.
When attaching the cables, for a LUN-mapped channel pair, make sure that the
first channel is connected to the upper port and the second channel is connected
to the lower port of the second channel.
For example, to provide redundancy, map half of the LUNs across Channel 0 (PID
40) and Channel 4 (PID 42), and then map the other half of your LUNs across
Channel 1 (SID 41) and Channel 5 (SID 43)
■ Point-to-point mode allows a maximum of 128 LUNs per array. In a redundant
configuration, 32 LUNs are dual-mapped across two channels on the primary
controller, and another 32 LUNs are dual-mapped across the secondary controller,
for a total of 64 distinct LUNs.
■ To use more than 64 LUNs, you must change to “Loop only” mode, add host IDs
to one or more channels, and add 32 LUNs for each additional host ID.
Note – When in loop mode and connected to a fabric switch, each host ID is
displayed as a loop device on the switch so that, if all 16 IDs are active on a given
channel, the array looks like a loop with 16 nodes attached to a single switch FL
port.
In public loop mode, the array can have a maximum of 1024 LUNs, where 512
LUNs are dual-mapped across two channels, primary and secondary controller
respectively.
5.3.2 A SAN Point-to-Point Configuration Example
A point-to-point configuration has the following characteristics:
■ In SAN configurations, the switches communicate with the Sun StorEdge Fibre
Channel array host ports using a fabric point-to-point (F_port) mode.
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