Sun Microsystems StorEdge 6900 Series - Manual (Page 105)

Chapter 7 Troubleshooting Virtualization Engine Devices 89
For Internal Use Only
Sun StorEdge 6900 Series Multipathing
Example
One Sun StorEdge T3+ array partner pair with 1
500GB RAID 5 LUN per brick (2 LUNs total)
Currently, there is one 10GB VLUN created from each physical LUN, for a total of
two VLUNs. In a Sun StorEdge 6900 series, there are four possible physical paths to
each Sun StorEdge T3+ array Volume (LUN). Refer to
FIGURE 7-4 and FIGURE 7-3 .
For example, to access the LUN on the Alt-Master, the Sun StorEdge T3+ array I/O
could travel:
■ From HBA-0 -> Switch -> SVE(1) -> Switch -> Alt-Master Controller (Primary
Route from HBA-0)
■ From HBA-0 -> Switch -> SVE(1) -> Switch -> Switch -> Master Controller ->
Backend Loop to Alt-Master (Secondary Route from HBA-0)
■ From HBA-1 -> Switch -> SVE(2) -> Switch -> Switch -> Alt-Master Controller
(Primary Route from HBA-1)
■ From HBA-1 -> Switch -> SVE(2) -> Switch -> Master Controller -> Backend Loop
to Alt-Master (Secondary Route from HBA-1)
The virtualization engine recognizes the primary (active) and secondary (passive)
pathing for the LUNs and routes the I/O to the primary controller, unless there is a
pathing failure to the primary path. In this case, the virtualization engine initiates a
LUN failover and routes the I/O through the secondary path (which, in turn, goes
through the interconnect cables). Refer to
FIGURE 7-6 .
The host, using multipathing software, is presented two primary (active) paths for
each LUN, allowing the host to route I/O through either or both HBAs.
In the event of a path failure before the second tier of Sun StorEdge network FC
switch-8 and switch-16 switches (refer to
FIGURE 7-5 ), one of the paths is disabled,
but the other path continues sending I/O as normal and takes over the entire load.
No Sun StorEdge T3+ array LUN failure is noted because of the redundant path by
way of the Sun StorEdge network FC switch-8 and switch-16 switch T Ports.