Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010, Руководство администратора, Страница: 58 / 140

58 SLES 11: Storage Administration Guide
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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 (Worldwide 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
directory. Because device node names in the form of
/dev/sdn
and
/dev/dm-n
can change on reboot, referring to multipath devices by their ID is preferred.
The multipath device names in the
/dev/mapper
directory reference the ID of the LUN and are
always consistent because they use the
/var/lib/multipath/bindings
file to track the
association. These device names are user-friendly names such as
/dev/disk/by-id/dm-uuid-.*-
mpath-.*
.
You can specify your own device names to use via the ALIAS directive in the
/etc/
multipath.conf
file. Alias names override the use of ID and
/dev/disk/by-id/dm-uuid-.*-
mpath-.*
names.
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
settings, see the
/usr/share/doc/packages/multipath-
tools/multipath.conf.synthetic
file.
1 In a terminal console, log in as the
root
user.
2
Open the
/etc/multipath.conf
file in a text editor.
3 Uncomment the
Defaults
directive and its ending bracket.
4 Uncomment the
user_friendly_names option
, then change its value from No to Yes.
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
alias
directive in the
multipath
section.
For example:
multipath {
wwid 26353900f02796769
alias sdd4l0
}
6 Save your changes, then close the file.
Blacklisting Non-Multipathed Devices in /etc/multipath.conf
The
/etc/multipath.conf
file should contain a
blacklist
section where all non-multipathed
devices are listed. For example, local IDE hard drives and floppy drives are not normally
multipathed. If you have single-path devices that
multipath
is trying to manage and you want
multipath
to ignore them, put them in the
blacklist
section to resolve the problem.