HP StorageWorks External Storage XP user guide (T1706-96006, June 2006)

Table Of Contents
24 Preparing for External Storage XP operations
For more information about path status, see ”Adding alternate paths by selecting multiple external LUs
(Add Paths)” on page 91.
Alternate path mode is Multi mode
Figure 5 shows an example of when the alternate path mode is Multi mode. When an error occurs in
one path, I/Os execute using paths other than the error path.
NOTE: As you restore the error path, use of the restored path automatically resumes.
Figure 5 Alternate path mode is Multi mode
NOTE: In Multi mode, active I/O load balancing occurs across external array ports and
controllers. The XP and EMC DMX are examples of external arrays that use Multi mode.
Alternate path mode is Single mode
Figure 6 shows an example of when the alternate path mode is Single mode. When an error occurs in
the path used for I/Os, the I/O execution path switches to the path with the second highest priority.