Using A Script To Set Path Priorities; Configuring Alua - Novell LINUX ENTERPRISE SERVER 10 SP3 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual

5.6.3 Using a Script to Set Path Priorities

You can create a script that interacts with DM-MP to provide priorities for paths to the LUN when
set as a resource for the
prio_callout
First, set up a text file that lists information about each device and the priority values you want to
assign to each path. For example, name the file
for each path in the following format:
host_wwpn target_wwpn scsi_id priority_value
Return a priority value for each path on the device. Make sure that the variable
FILE_PRIMARY_PATHS resolves to a real file with appropriate data (host wwpn, target wwpn,
scsi_id and priority value) for each device.
The contents of the
primary-paths
0x10000000c95ebeb4 0x200200a0b8122c6e 2:0:0:0 sdb
3600a0b8000122c6d00000000453174fc 50
0x10000000c95ebeb4 0x200200a0b8122c6e 2:0:0:1 sdc
3600a0b80000fd6320000000045317563 2
0x10000000c95ebeb4 0x200200a0b8122c6e 2:0:0:2 sdd
3600a0b8000122c6d0000000345317524 50
0x10000000c95ebeb4 0x200200a0b8122c6e 2:0:0:3 sde
3600a0b80000fd6320000000245317593 2
0x10000000c95ebeb4 0x200300a0b8122c6e 2:0:1:0 sdi
3600a0b8000122c6d00000000453174fc 5
0x10000000c95ebeb4 0x200300a0b8122c6e 2:0:1:1 sdj
3600a0b80000fd6320000000045317563 51
0x10000000c95ebeb4 0x200300a0b8122c6e 2:0:1:2 sdk
3600a0b8000122c6d0000000345317524 5
0x10000000c95ebeb4 0x200300a0b8122c6e 2:0:1:3 sdl
3600a0b80000fd6320000000245317593 51
To continue the example mentioned in
. You can use any path and filename. The script does the following:
sbin/path_prio.sh
On query from multipath, grep the device and its path from the
file.
paths
Return to multipath the priority value in the last column for that entry in the file.

5.6.4 Configuring ALUA

The
mpath_prio_alua(8)
command. It returns a number that is used by DM-MP to group SCSI devices with the same priority
together. This path priority tool is based on ALUA (Asynchronous Logical Unit Access).
"Syntax" on page 66
"Prerequisite" on page 66
setting.
/usr/local/etc/primary-paths
file for a single LUN with eight paths each might look like this:
Table 5-5 on page
command is used as a priority callout for the Linux
61, create a script named
/usr/local/etc/primary-
multipath(8)
Managing Multipath I/O for Devices
. Enter one line
/usr/local/
65