Installation guide

Appendix C. Multipath-usage.txt File for Red Hat Enterprise Linux 4
Update 3 161
For some conditions, that may not be sufficient. If DM-MP is
multipathing devices that you do not want it to work on, you can
blacklist the devices by either device name or WWID.
NOTE: It is safest to blacklist individual devices by WWID, because
their device names may change.
Several other configuration options are detailed later in this
document. To check the effects of configuration changes, you can
do a dry run with the following command:
# multipath -v2 -d
3. Set the multipathd init script to run at boot time. by issuing
the commands
# chkconfig --add multipathd
# chkconfig multipathd on
4. start dm-multipath (This is only necessary the first time. On
reboot, this should happen automatically).
# multipath
# /etc/init.d/multipathd start
After initial setup, all access to the multipathed storage should go
through the multipath device.
Configuration File:
Many features of DM-MP are configurable using the configuration file,
/etc/multipath.conf.
For a complete list of all options with descriptions, refer to
/usr/share/doc/device-mapper-multipathd-0.4.5/multipath.conf.annotated
The configuration file is divided into four sections: system defaults,
blacklisted devices (devnode_blacklist), per storage array model settings
(devices), and per multipath device settings (multipaths). The per
multipath device settings are used for the multipath device with a
matching "wwid" value. The per storage array model settings are used
for all multipath devices with matching "vendor" and "product" values.
To determine the attributes of a multipath device, first the per
multipath settings are checked, then the per controller settings, then
the system defaults. The blacklisted device section is described
setup step 2.
NOTE: There are compiled-in defaults for the "defaults",