Novell LINUX ENTERPRISE SERVER 10 SP2 - STORAGE ADMINISTRATION GUIDE 05-15-2009 Administration Manual page 63

Multipath Attribute Description
prio_callout Specifies the program and
arguments to use to
determine the layout of the
multipath map.
When queried by the
multipath
specified mpath_prio_*
callout program returns the
priority for a given path in
relation to the entire multipath
layout.
When it is used with the
path_grouping_policy of
group_by_prio, all paths with
the same priority are grouped
into one multipath group. The
group with the highest
aggregate priority becomes
the active group.
When all paths in a group fail,
the group with the next
highest aggregate priority
becomes active. Additionally,
a failover command (as
determined by the hardware
handler) might be send to the
target.
The mpath_prio_* program
can also be a custom script
created by a vendor or
administrator for a specified
setup.
A %n in the command line
expands to the device name
in the
A %b expands to the device
number in major:minor format
in the
A %d expands to the device
ID in the
directory.
If devices are hot-pluggable,
use the %d flag instead of
%n. This addresses the short
time that elapses between the
time when devices are
available and when
creates the device nodes.
Values
If no
are equal. This is the default.
/bin/true Use this value when the
group_by_priority is not being used.
The
command, the
when queried by the
program names must begin with
and are named by the device type or balancing
method used. Current prioritizer programs
include the following:
/sbin/mpath_prio_alua %n Generates path
priorities based on the SCSI-3 ALUA settings.
/sbin/mpath_prio_balance_units Generates
the same priority for all paths.
/sbin/mpath_prio_emc %n Generates the path
priority for EMC arrays.
/sbin/mpath_prio_hds_modular %b
Generates the path priority for Hitachi HDS
Modular storage arrays.
/sbin/mpath_prio_hp_sw %n Generates the
path priority for Compaq/HP controller in active/
standby mode.
/sbin/mpath_prio_netapp %n Generates the
path priority for NetApp arrays.
/sbin/mpath_prio_random %n Generates a
random priority for each path.
/sbin/mpath_prio_rdac %n Generates the path
priority for LSI/Engenio RDAC controller.
/sbin/mpath_prio_tpc %n You can optionally
directory.
/dev
use a script created by a vendor or administrator
that gets the priorities from a file where you
specify priorities to use for each path.
/dev directory.
/usr/local/sbin/mpath_prio_spec.sh %n
Provides the path of a user-created script that
/dev/disk/by-id
generates the priorities for multipathing based on
information contained in a second data file. (This
path and filename are provided as an example.
Specify the location of your script instead.) The
script can be created by a vendor or
administrator. The script's target file identifies
each path for all multipathed devices and
specifies a priority for each path. For an
udev
example, see
Set Path Priorities," on page
attribute is used, all paths
prio_callout
programs generate path priorities
prioritizer
multipath
Section 5.6.3, "Using a Script to
65.
Managing Multipath I/O for Devices
command. The
mpath_prio_
63