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第 4 章 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 themselves support DM Multipath. For information on the default configuration values, including supported devices, run either of the following commands. 
# multipathd show config
# multipath -t
You can override the default configuration values for DM Multipath by editing the /etc/multipath.conf configuration file. If necessary, you can also add a storage array that is not supported by default to the configuration file.

注意

You can run set up multipathing in the initramfs file system. If you run multipath from the initramfs file system and you make any changes to the multipath configuration files, you must rebuild the initramfs file system for the changes to take effect. For information on rebuilding the initramfs file system with multipath, see 第 3.4 节 “Setting Up Multipathing in the initramfs File System”.
This chapter provides information on parsing and modifying the multipath.conf file. It contains sections on the following topics:
  • 配置文件总览
  • 配置文件 blacklist
  • 配置文件 defaults
  • 配置文件 multipaths
  • 配置文件 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. 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.
配置文件允许常规表达式描述语法。
Further information about the configuration file can be found on the multipath.conf(5) man page.

4.1. 配置文件总览

多路径配置文件可分为以下几个部分：
blacklist
Listing of specific devices that will not be considered for multipath.
blacklist_exceptions
列出除了根据黑名单部分的参数可能会被列到黑名单中的多路径候选人。
defaults
General default settings for DM Multipath.
multipaths
各个独立多路径设备的特性设置。这些数值覆盖了在配置文件的 defaults 和 devices 部分中指定的数值。
devices
各个存储控制器的设置。这些数值覆盖了在配置文件的 defaults 部分指定的数值。如果您要使用不是默认支持的存储阵列，您可能需要为您的阵列创建 devices 子部分。
When the system determines the attributes of a multipath device, first it checks the multipath settings, then the devices settings, then the multipath system defaults.