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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
You can override the default configuration values for DM-Multipath by editing the
/etc/multipath.confconfiguration file. If necessary, you can also add a storage array that is not supported by default to the configuration file.
You can run set up multipathing in the
initramfsfile system. If you run multipath from the
initramfsfile system and you make any changes to the multipath configuration files, you must rebuild the
initramfsfile system for the changes to take effect. For information on rebuilding the
initramfsfile system with multipath, see Section 3.4, “Setting Up Multipathing in the initramfs File System”.
This chapter provides information on parsing and modifying the
multipath.conffile. 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
multipath.conf.defaultsfile. 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
4.1. Configuration File Overview
The multipath configuration file is divided into the following sections:
- Listing of specific devices that will not be considered for multipath.
- Listing of multipath candidates that would otherwise be blacklisted according to the parameters of the blacklist section.
- General default settings for DM-Multipath.
- Settings for the characteristics of individual multipath devices. These values overwrite what is specified in the
devicessections of the configuration file.
- Settings for the individual storage controllers. These values overwrite what is specified in the
defaultssection of the configuration file. If you are using a storage array that is not supported by default, you may need to create a
devicessubsection for your array.
When the system determines the attributes of a multipath device, first it checks the multipath settings, then the per devices settings, then the multipath system defaults.