Installation guide

Chapter 4. The DM-Multipath Configuration File
By default, DM-Multipath provides configuration values for the most common uses of multipathing. In
addition, DM-Multipath includes support for the most common storage arrays that support DM-Multipath.
The default configuration values and the supported devices can be found in the
/usr/share/doc/device-m apper-multipath-0.4.5/m ultipath.conf.defaults file.
Note
The location and contents of the m ultipath.conf.defaults file may differ slightly from the
example shown in this chapter depending on the release of RHEL 4 that you are running.
You can override the default configuration values for DM-Multipath by editing the
/etc/m ultipath.conf configuration file. If necessary, you can also add a storage array that is not
supported by default to the configuration file. T his chapter provides information on parsing and modifying
the m ultipath.conf file. It contains sections on the following topics:
Configuration file overview
Configuration file blacklist
Configuration file defaults
Configuration file multipaths
Configuration file devices
In the multipath configuration file, you need to specify only the sections that you need for your
configuration, or that you wish to change from the default values specified in the
m ultipath.conf.defaults file. If there are sections of the file that are not relevant to your
environment or for which you do not need to override the default values, you can leave them commented
out, as they are in the initial file.
The configuration file allows regular expression description syntax.
An annotated version of the configuration file can be found in /usr/share/doc/device-mapper-
m ultipathd-0.4 .5/m ultipath.conf.annotated.
4.1. Configuration File Overview
The multipath configuration file is divided into the following sections:
devnode_blacklist
Listing of specific devices that will not be considered for multipath. By default all devices are
blacklisted. Usually the default devnode_blacklist section is commented out.
defaults
General default settings for DM-Multipath.
multipaths
Settings for the characteristics of individual multipath devices. These values overwrite what is
specified in the defaults and devices sections of the configuration file.
Red Hat Enterprise Linux 4 DM Multipath
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