Novell LINUX ENTERPRISE SERVER 10 SP3 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual page 57

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Paths are grouped into priority groups. Only one priority group is ever in active use. To model an
active/active configuration, all paths end up in the same group. To model active/passive
configuration, the paths that should not be active in parallel are placed in several distinct priority
groups. This normally happens automatically on device discovery.
The output shows the order, the scheduling policy used to balance I/O within the group, and the
paths for each priority group. For each path, its physical address (host:bus:target:lun), device node
name, major:minor number, and state is shown.
Configuring User-Friendly Names or Alias Names in /etc/multipath.conf
A multipath device can be identified by either its WWID or an alias that you assign for it. The
WWID (World Wide Identifier) is an identifier for the multipath device that is guaranteed to be
globally unique and unchanging. The default name used in multipathing is the ID of the logical unit
as found in the
/dev/disk/by-id
and can change on reboot, referring to multipath devices by their ID is preferred.
/dev/dm-n
The multipath device names in the
always consistent because they use the
association. These device names are user-friendly names such as
You can specify your own device names to use via the ALIAS directive in the
file. Alias names override the use of ID and
multipath.conf
IMPORTANT: We recommend that you do not use aliases for the root device, because the ability to
seamlessly switch off multipathing via the kernel command line is lost because the device name
differs.
For an example of
multipath.conf
tools/multipath.conf.synthetic
1 In a terminal console, log in as the
2 Open the
/etc/multipath.conf
3 Uncomment the
Defaults
4 Uncomment the
user_friendly_names option
For example:
## Use user friendly names, instead of using WWIDs as names.
defaults {
user_friendly_names yes
}
5 Optionally specify your own user-friendly names for devices using the
section.
multipath
For example:
[ready ]
[ready ]
directory. Because device node names in the form of
directory reference the ID of the LUN and are
/dev/mapper
/var/lib/multipath/bindings
settings, see the
/usr/share/doc/packages/multipath-
file.
user.
root
file in a text editor.
directive and its ending bracket.
, then change its value from No to Yes.
file to track the
.
mpath0
/etc/
names.
/dev/mapper/mpathN
directive in the
alias
Managing Multipath I/O for Devices
/dev/sdn
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