HP XP Racks - Manual (Page 38)

Priority of Switching Destination Paths
Priority of paths varies depending on the architecture of the host machine.
If the architecture of the host is CHRP, the switching destination path is
selected based on four keys. First, the path with the smallest path priority
number (first key) is selected. If there are multiple paths with the smallest
path priority number, the order for selecting a unique path is smallest slot
number (second key), smallest CHA port number (third key), and smallest
PATH_ID value (fourth key).
If the architecture of the host is not CHRP, the switching destination path is
selected based on three keys. First, the path with the smallest path priority
number (first key) is selected. If there are multiple paths with the smallest
path priority number, the order for selecting a unique path is smallest CHA
port number (second key) and then smallest PATH_ID value (third key).
This sub-section explains these keys.
Path priority number
This number indicates the priority level set for each path. Priority levels
can be set from 1 to 255. The lower the number, the higher the priority.
The default is 1. The priority level is set by using OS commands. The
following shows an example of the procedure for setting the path priority
number.
a
.
Execute a command that displays the path information for the LU:
# lspath -l hdisk4 -F"name parent path_id connection
path_status status"
hdisk4 fscsi0 0 50060e8005271720,31000000000000 Available
Enabled
hdisk4 fscsi1 1 50060e8005271730,31000000000000 Available
Enabled
hdisk4 fscsi2 2 50060e8005271740,31000000000000 Available
Enabled
hdisk4 fscsi3 3 50060e8005271750,31000000000000 Available
Enabled
b
.
Execute a command that displays the information for the path whose
path priority number you want to set:
# lspath -l hdisk4 -p fscsi0 -w
50060e8005271720,31000000000000 -E
scsi_id 0x651400 SCSI ID False
node_name 0x50060e8005271720 FC Node Name False
state Enabled N/A True
priority 1 N/A True
c
.
Execute a command that changes the path priority number:
# chpath -l hdisk4 -p fscsi0 -w
50060e8005271720,31000000000000 -a priority=5
path Changed
2-16
HDLM Functions
Hitachi Dynamic Link Manager (for AIX) User Guide